A CRY FOR HELP

Hi everyone I am 15 this yr and i have NEVER had sex though i do masturbate alone at times.My first period started october last year and I haven’t been having regular periods since.I missed november and december (with light bleeding) and for Jan and Feb this yr they are absolutely normal.Then just when I thought they were settling down, the problem starts again–this time worse than ever.I missed my period again in March and April and since then my period became very light, lasting 1 or 2 days, and vaginal discharge for the next whole week.It is already July now and the problem still persists.The problem is, although i am having vaginal discharge, i feel them like periods and there is a weird smell.Could this be an infection or is it caused by stress from school or even hormonal balance? (p.s I thought the symptoms were similar to pregnancy at first but then i havent been nauseous or vomitting plus i nvr had sex -.-) I m underweight slightly for my height 48.5kg and 1.66m tall, and i abstain from seafood since i was 12.But these shouldnt pose any much problems, should they?My peers are about the same weight as me but they have no problems with irregular periods.Sorry for the long forum but i have to add this—I havent been gaining much weight except around 1kg since i missed my march period and i dont feel so well without them.I have been feeling a lot of gas in my chest (burping) but i thought it could be due to caffeine withdrawl coz i tried to abstain from coke since i missed my period.Any professionals or experienced adults who happened to read this please offer me some comments and help.Thx!!!