Me personally I think you and your fiance should talk about this together
I say go for it . You are young . Im 22 and trust me Ive been a mom since 14 . and im proud of it you won't regret it i mean i took a long shot at that age but im happy .
You're an adult, you're more than capable of making your own decisons! Congratulations on wanting to be a mommy! I say go for it. Fertility doesn't last forever, especially for women, and at least you'll have the energy for it. The closer you are to peak fertility (about age 24) the more likely you are to have no complications with your pregnancy. I wish there were more people like you out there. Most people our age want to be kids forever themselves. I praise your maturity!!
I think you should wait a while. I had my first child a 16 and when I was 19 I felt as if I missed my teen years. I had my 2nd child at 22 and I'm 5 1/2 weeks pregnant at 40... I would say 22-25 would be a great age. Enjoy your early 20's and it will give you guys sometime to get to know each other as a married couple. The first so many years are the hardest and being so young might make it even harder then adding a child. With that said this is only my opinion I don't know you and based on what you said you seem more together then I was at 18 and most 18 years I know.
I was pregnant when I was 18 gave birth when I was 19 and I'm currently pregnant with my second at 21 this is going to be my last. It's not easy but it is do able. I say Go for it your in a stable home and relationship. And as for missing out on your life your not missing anything. And you will grow and develop in a different way. I have no regrets of having my son and soon daughter early. Good luck:)
A baby could put a strain on your relationship enjoy being newlywed for a while enjoy eachothers company before you bring a baby into the middle of all of it