Yes. My house was like that. In fact the only thing that really got me out of it was meeting DH (who wooed me by coming over and doing my mountains of washing up repeatedly 
) and moving to a smaller place abroad where I had to let go of 60% of our stuff (because of shipping costs) and then DH basically drives the cleaning efforts in this place, because if he's ill for a few days, it starts to creep into chaos again.
Sorry, that's not entirely helpful. But taking DH out of the equation, what has actually helped is
- Less stuff
- Set routines
- Actually keeping to those routines (this is probably the hardest part!)
Also, starting from zero.
I am actually pursuing assessment for ADHD (inattentive) now because I eventually understood that struggling so much with such basic things was not normal and it's not just a case of me being lazy. (There are other issues as well) Depression can also cause the lethargy, it's a case of not valuing yourself enough to want to clean up for you. I always wanted to and intended to but was consistently confused at why I failed and then that transferred into self-loathing which lead to depression which then made me not care. 
Even now when DH reminds me of something I am often surprised that it's come up again so soon.
I did actually have SS involvement at one point and my landlord was really unhappy and warned that he may take steps towards eviction. So it does have serious consequences reaching beyond yourself, even if you feel happy living in the crap (which it sounds like you don't.)
So action plan.
First of all you need to accept that it's actually a problem and decide that you really are going to change it. Chase away all those negative "But..." thoughts, because they are not going to defeat you this time.
If you're having trouble really caring about it or you're finding that your self-flagellation is getting in the way of actually doing anything about it, then it would be a good idea to see your GP about treatment for depression as a first port of call.
If you're feeling tired/lethargic/lacking energy but not depressed (surprisingly common 1 year after childbirth), get blood tests to make sure your iron, thyroid, etc, levels are okay and flag up any need for supplements. Your GP can organise this if you ask. If you really can't face this then buy some Berocca and vitamin D because those two are the most common, but it's better to get a proper picture of what might be going on.
If you're constantly trying but not really getting anywhere then try the methods first and if it's not getting any better then it might be worth looking at why as part of a bigger picture.
Second - ASK for help. Admit to friends and family that it's got out of control and ask if they will come round one weekend and help you get it sorted. Don't worry at this point that it's going to be a waste and it will just get bad again, because it won't, as long as you follow the process through to the end. There is nothing so insurmountable that you can't deal with it. If you can't ask anybody and you have money to throw at the problem, you could call around cleaning companies to ask about any who do a deep clean.
Third - you want to do a radical downsize. Two ways of doing this that I can suggest: Virtual move Order some moving boxes (£16 for a set on amazon) or collect some of those crates from supermarkets, and pack every single thing in your house up, leaving those you are immediately using for last. As you pack, ask yourself if you were moving to another country and were limited on what you could take, whether you would pack this item. If the answer is no, then let it go - charity shop, car boot, bin, whatever. Don't worry too much about sustainability etc at the moment because this is more of an emergency situation. You need to set aside time for this - take time off work, get childcare, get people to come and help you, etc.
The other way that I know to be effective is the KonMari method. This is thread 9 and it's only just started so very little discussion yet but basically it revolves around this book, which is a very sweet if slightly odd book about decluttering by a charmingly bonkers Japanese woman which claims to be life changing, and by all accounts really seems to be. It is quite magic and I am finding it helpful, even if I am the slowest person in the world to ever trudge through it!
Fourth: (And you can do this alongside the KonMari book if you like) - develop new systems and routines. There are a hundred ways to do this but I would say the most important thing is to keep it simple, and make things easy for yourself by interrupting destructive habits and creating shortcuts. It's fine to have a laundry basket downstairs to chuck discarded clothes in rather than have them lying around, if you find yourself leaving plates lying around, interrupt that by changing where you eat, have small wastepaper bins around to catch rubbish which is discarded wherever, buy a tabletop dishwasher if you have no room for an under counter one (have fewer plates to force yourself to wash up immediately, and make it never too large of a task). etc. Too many systems to outline here, but here are some ideas and names to google:
FLYlady, Unfuck Your Habitat, an android app called Regularly, various task list/home routines apps, a laminated list you stick to the fridge, designating certain hours of the day "work hours" where you do housework, 7 habits of highly efficient households, a daily maintenance routine, four lists (morning, naptime, dinnertime, bedtime), walk through the house and start with whatever you notice, Kim & Aggie, a "Waterfall" method where you walk through the house tackling all of the "low hanging fruit" (easy, v. low effort jobs) and make a mental note of what larger jobs need doing so you can come back to them, involving DD in jobs so that it becomes a game and time spent with her but you also get stuff done (albeit slowly), 50s housewife routines (can find on google).... probably a hundred more.
Lastly: Keep on top of it. As I said, this is the hardest part. It might mean outsourcing, it might mean having a friend drop in once a week, it might mean logging things in an app, it might mean going to the doctor and asking for more support with mental health whether that is assessment for some kind of executive function issue or treatment for depression. (And yes ask for different meds if the others made you feel flat), it might mean getting therapy for some long-running issue. It might mean continually assessing systems to interrupt inefficient/unhelpful parts, it might mean using disposable plates, or whatever. It might just mean accepting that housework takes longer (daily) than you would ideally like to spend doing it. That's not a very fun realisation, but it helps to accept it.
There was a website I used to look at called Squalor Survivors. That showed some houses which were utterly terrifying in the amount of (literal) crap that was in them. It might be helpful for you or it might be the opposite, but for me it reminded me that it doesn't matter how bad a house is, it's always cleanable. Kim and Aggie also has this effect, when that used to be on. It's always doable, it might not feel it, but it's just something getting in the way. Find that thing and you kill the monster in its heart, not one of the ever growing heads.
You can do it! :)