alot of vaginal bleeding before for long periods of time,now periods are rare.

i'm 23 years old and when i was about 19 years old i began bleeding alot, it was like a period that would last for 3 weeks at a time and go away for a few days and then begin again. i know i should have gone to the doctor at the time but i was scared and didnt tell anyone. well this kept hapenning for about a year and when it would be heavy, huge blood clots would come out. i never had any abdominal pain and i wasnt or had i ever been sexually active. i did notice that i gained alot of weight even though i didn't eat much.this eventually stopped after a year and i became happy because my period was begining to be regular for about a year,therefore i thought everything was okay. well about a year ago i became sexually active with my fiance and maybe a few months ago my period started becoming very irregular. to the point where now i miss it every other month and when i do get it. it's very light. so light that it looks like spotting. my questions are, what happened to me when i was younger? could i be infertile? will it be hard for me to become pregnant because i don't have regular periods now? could i have some sort of cervical cancer or HPV?