What is a family supposed to feel like?

I'm a new mom of a beautiful 3 month old girl. My boyfriend has two kids of his own who I love... 

Though it seems like ever since having the baby, I just don't feel like a family. I feel divided from them, constantly annoyed with my boyfriend and just far... Far from what I thought we should be doing as a new family. Is this common? Will it pass? I feel resentful a lot of the time... Like he can go out and have breaks, and I'm home w baby all he time. I feel like he doesn't prioritize us enough... He doesn't put us first. But then I wonder if I'm just hormonal? I don't trust my emotions but they are running me all over the place these days. I was so fine until about a month ago. I don't want to strain our relationship but a lot of the time I just don't feel happy. I love my baby but I get annoyed when the kids are here... Even though I adore them. I get annoyed that he doesn't pick the baby up more, but whenever he does I wish he'd just give her back to me. I am all over the place. Can anyone relate?