Scared to get pregnant again!

I got pregnant at the end of my junior year at 17 and every since then I am terrified to get pregnant again.. Even when I get married. Idk about other teen moms but that really scarred me for life. Being a teen mom is one of the hardest thing I had to do ever. I'm almost 20 now and even when I have protected sex I am paranoid about getting pregnant and be worried until I get my next period. HELP! HOW CAN I HAVE GET OVER THIS FEAR!😐