WHAT'S WRONG WITH ME !! Got period twice in one month again?!!?

i got my period twice in march one on march 3rd then again on march 29 then i didnt get it in april. then i got my period twice in may one on may1st and the other may 31st but i didnt get my period in june does the second periods count for the month i missed? and why does this seem to keep happening to me? and i'm still a virgin so i can't be pregnant.i forgot to mention that i'm 20 years old and i had my period since i was 13 and i never took birth control i never had sex but i did get fingered could that be tha cause also please help i'm freaking out