Oh dear Amber.
Lots of good advice.
I think we're pretty similar and have pretty similar DH's too. So for example - DH would just not notice the mess and not bother at all if mil arrived and had to tidy up/make lunch herself and so he doesn't see why for me it would be an issue. Our domestic standards are just not the same.
So definitely throw some money at the problem. I so remember DH pointing out to me on one very black day that I'd had some time to myself as I'd had a bath - yes, that's a basic hygiene requirement!
How were things when you were back at work after DS? Presumably your DH stepped up more when you were both out working?
I do know that sleep deprivation is a killer - I never did any sleep training but DD did get a lot better at around 10 months. I know its not a popular view but I do think a lot of bf babies don't sleep through until around a year unfortunately.
Are you ready to stop bf? Perhaps cracking on with that would help and also when is DD due to start nursery - any chance she could start going for a day a week so you can catch up on some rest before going back to work.
Was lovely to meet the very beautiful Red yesterday - am sure people thought I was out with my daughter 
Have spent the morning make cake and scones for FIL's birthday but now DS2 poorly so i'm staying at home on the sofa with him. Good job as spent lunch telling DD not to spill soup down her dress and promptly splashed it all over myself.