Hi Moon yes, it does get easier and yes, you will get your life back
and no you are most certainly not doing a crap job - based on the fact that your job is to grow that tiny, little baby into a big boy and he's put on a whole pound this week.
It's really hard when they are tiny as you and your dh feel like you are living separate lives - I clearly remember it with all mine that you end up writing off the first three to 5 months. I also remember choosing to ignore the books pretty quickly - you know all those booked that said to get the baby to sleep in the evening, you need to do evening feeds in a quiet dark room? yeah, right - even with my first, we were back downstairs really quickly so that I saw dh.
I can't give much advice on breastfeeding as I didn't do it for very long as mine didn't get enough milk from me but I know there are plenty on here who can give advice and am sure they will be along soon.
What I can give advice on is to do what it takes to get through this - with DD1, at 1 month we moved from breast to bottle and she became a different baby, slept well, got into a lovely routine and I loved my mat leave. With DS, he settled during the evenings really well but woke early and would not get into any sort of routine - for the first month, he pretty much slept with us and we shared the morning chorus - I went back to work when he was 5 months and was pretty knackered as he always woke before 5, often much earlier. I remember lots of going to bed early in evenings with him. With DD2, well. we co slept for the first 3 months at least - I didn't even share a room with DH until she was at least 6 months as we needed sleep and we all slept better that way. I found my sling invaluable as again, routine was not her thing.
So, you know your baby best and you also know yourself - could you got to bed really early some evenings? I know it will feel like you get even less time with DH but a couple of good nights sleep will make you feel much better. Go with the flow, expect to be tired at work - also expect for it to feel much less important and congrats on the weightloss Stop beating yourself up - you're a great mum, doing a great job and you just need to believe it