fiancé came out as trans

My fiancé came out as trans a short while ago and I'm not sure what to do. He says recently he's felt like boy wasn't the right title. He's always been really feminine and he likes it when I do his  makeup and it's part of why I love him, but I'm worried about how far he wants to go. He says that he's never been fully comfortable with his body but he didn't think that much about it until recently because of how supportive I have been of his feminine side. 
The thing is though that we both want kids, but he seems to want to have surgery. We can't afford it right now but I'm worried about the future. As much as I want to support him and help him I also really like the way he is now. I now that's not everything and his personality is what matters, but I fell in love with who he is now and I've grown to feel comfort just by looking at him and hugging and cuddling him and I'm worried about that changing. 
Anyone else experience this? Any advice?