Is this normal?

My SO and I had a baby 4.5 months ago, since then most of the time I feel as though I'm just not connecting with my SO anymore and sometimes I feel like I just don't like him anymore. He gets mad a lot when our son gets fussy and gets super impatient. What I mean by that is we just don't spend a lot of time together anymore and I feel as though he expects me to do all the work related to our son, I work 40+ hours a week and he is a student/works at the university. He expects me to put our son to sleep, feed him throughout the night, wake up at 5 for work, take care of our baby if he wakes up while I'm getting ready, pick him up from daycare and take care of him until I put him to sleep again. When I want to go do something he isn't very receptive to giving me time to myself, yet he still goes out on the weekends. When we're out with our friends and I want to stay a little later I can't because I have to take care of our son. I love my son, he is the best thing that's ever happened to me, sometimes I think I'd be happier raising him on my own compared to raising him with my SO.. I'm supposed to be planning our wedding soon and when I think about it I just honestly don't think I want to get married. I find that I'm happiest either while I'm at work or just hanging out with our son alone. Is this normal? Has anyone that's a first time mom been through this and can give me advice? I want to love my SO again like I use to, I'm just worried it's not going to happen.