I'm not trying to be controlling but...

I had a talk with my man and he wants to donate sperm for money, and he was asking my opinion. (We are engaged). I said that I didn't want him to do that, that I want to have his babies and also, you never know who could possibly mother your children...could be anyone. Could be bad people. I dunno. I felt as though since we are engaged I should be able to express my concerns and be respected, especially in the sense that I love him and I want to have all the babies he's gonna have, but he doesn't see it that way. Am I being too controlling or selfish?