I think it's a really difficult time when you are a new mum to young children, especially when you add in breastfeeding.
You have suddenly given up your entire life and your DH's life is pretty much as it was before. I used to feel exactly the same resentment with my husband.
I was being held prisoner with a newborn and a toddler and he was still able to go to work every day, go to the gym, play sports at the weekend etc. Even went on the odd stag do!
None of these things are a big deal and the truth is I didn't actually want to do any of those things myself, I was just frustrated that I couldn't without a pre-arrangement.
It's a massive adjustment, but it's temporary. And, I'm ready to be shot down for this comment, but I think it takes men a bit of time to realise that the children aren't 'yours' and they are equally responsible for them. Because pregnancy, breastfeeding, maternity leave etc. But if you've chosen a good man to have kids with then they adjust too and things get better.
It definitely took me returning to work to get my husband to really understand that he has children that he is jointly responsible for getting ready/nursery run/ packing bags/ sick days/ bedtime and so on.
I remember one morning I was exhausted, the house was chaos and DH was cheerily bouncing out the door to work. I said I wished I was the one that just got to 'piss off out' and we had a argument over whose life was more stressful 🥴
My children are both upper primary school now and those days are far behind us. Hang in there OP, it's a hard time in all relationships.