I'm 18 and ever since I was 13 I had my period only 2 (MAYBE 3) times a year. I'm scared that when I'm older I won't be able to get pregnant from lack of eggs because of how much I do bleed when I'm on my period. I want kids when I'm older REALLY bad and don't want to not figure this out and have it be too late.

It would be foolish and dangerous to diagnose your "problem" without running tests and conducting a physical examination.

You need to see a Physician.