Can't conceive.

My doctor told me I may not be able to have children when I'm older, I'm only 20 but would like to have 1 by 25, & another after. I've always wanted to be a mother but now I'm terrified. I've been off bc since I was 18 & my bf and I don't use condoms and I've never missed a period or had a pregnancy scare. I have an appt with my Gyno for Thursday to find out what's going on but I'm so scared. Just need a little uplifting!