Afraid it will cause problems.

My SO and I tried for like a month to conceive. I have to have a hysterectomy but am wanting to have one more child before I do. I have 2. SO has 0. He was on board for having a baby of his own and I had a chemical pregnancy. Then he decided he didn't want to do it and was unsure if he wanted kids of his own after all. After he decided that I was very disappointed and heart broken. I ended up unfollowing my cousin because she announced she is pregnant and invited me to her baby shower. She is 11 weeks. And my other cousin just announced his gf is pregnant and many other people around me are pregnant. I started crying this morning and said the universe is being very cruel. And then out of nowhere. Sex. And he did not pull out. I asked him what was going on after and he said I dunno. Figured I was horny why not. With him being so indecisive it is like a constant emotional roller coaster. And what if I get pregnant and he changes his mind again. I don't want to keep going on that ride. Any advice?