Can I get pregnate?

Hi my mane is kesia and my life partner and i have been talking about having children. we have the planns fror her. But what about me? I have my menstral every few months; somethimes it's heavy and will last 2-3 weeks and sometimes it's very light and will only last for 2-3 days! Can I have children?  Whats wrong with me? I am very young and very healthy. I an 21 and extreemly athletic! But my body seems to be crashing already! HELP!!