Anxiety about having kids one day...

My fiancé and I are getting married in a couple months. I’m super excited for that! He is REALLY pushing for us getting pregnant right away. I am DEFINITELY not opposed to the idea of having kids, but lately I’ve felt so anxious when I discuss that with him. I feel like we should wait but it doesn’t seem like he’s really listening. He keeps assuming it’s a “phase” and I’ll get excited once we actually get pregnant. I’m really not sure how to feel at this point, but I know it’s not a happy anxiety. I feel straight up terrified to know MY entire life will change with a kid. I’m a firefighter medic. My work life, the purpose in my life, will disappear while I deal with a pregnancy and later on an infant. I don’t know what to do and now I feel terrible. My mind almost drifts towards the idea of just not having kids for another decade or so but then I’ll have moments where I would love a child. All of our friends, literally, have children and we’re both so happy around them. But my life is so different, I can’t imagine being a stay at home mom. I can’t even stand having a single day off of work. I’m at a loss.