Anybody else have this fear?

Soooooo I'm 20. And I am a sophomore in college. I am also married to a wonderful man who is in the Army. Life is great for me right now, but there's this one fear that I can't seem to get over. I have this fear of infertility. I dont know why, but I hear so many stories about women not being able to conceive and I get nervous that that might become a part of my reality. My husband has a 1 year old daughter from a previous relationship, which I think is a reason why I'm so obsessed to find out if I'm healthy reproductive wise. I've never had any problems with my body. Never had an STD, dont drink or smoke, and I have pretty regular periods. But I'm always watching my health, watching what I eat just to make sure I dont screw up my body. My husband talks about having kids constantly. But I prefer to finish school first and become licensed Labor and Delivery nurse before I start pushing out his babies lol. Ladies, do you have any suggestions on how to get over this fear? Can you relate in any way? Thanks for your advice!

P.S. I've been around kids all my life. My mom took in kids from a foster care agency and I have tons of young children in my family. Plus, I had the nerve to work in a daycare on my college campus so babysitting is definitely not a suggestion for me lol.