you have a plethora of options, i don't think we could list all of them!
what i would do would be this:
give the AD's another go. promise yourself you will do it for a week. and then re-evaluate.
if not happy then see a different GP about it. ask about PND.
talk to your husband. or write him a letter! I did that with dp when ds1 was tiny and i wasn't coping. i found when we "discussed" stuff it ended in an argument. in a letter i could bullet point all the difficulties i had, all the things he could do to try and help me, and all the things he did that made it worse
- it was probably horrid for him to read, but it was something i needed to do, and it DID help
you need to start working together. he needs to try and help more with the baby, and you need to let him.
that might start with an arrangement that he takes baby out in the sling/buggy for an hour every sunday morning, allowing you time to go to the gym, or take a nice long bath and do your hair?
you need to talk to your mum, maybe see if she would sit for you once a fortnight or something. even if it was just for a couple of hours while you and dh go for a walk or out for a drink or 2. being together alone is important.
I honestly don't think that anything will change until you are effectively treating the depression tho. and you know that the only person who can do that is you.
it doesn't mean giving up breastfeeding if you don't want to, in fact from what you have said i would worry that giving up totally would give you awful feelings of guilt and possibly make it worse.
but there are several diff medications you can take while breastfeeding, so if the first one really, really doesn't work for you then you need to try something else. and you need to give it time to work