Scared....

I'm 19 and I've always had the mind set to have this such big family, have tons of children and have a husband.. But lately I've been so scared that im not able to have children.. 
​I've been getting these really bad pains near my ovaries for the past couple of months and do not know what to do.. The pains always come this time of the month when I am most fertile.. Does this happen to anyone else or just me?
​What should I do?