Irregular periods and pregnancy?

I have very irregular periods,My periods last for a week to at least 3 or 4 weeks.Me and my ex boyfriend had unportect alot.In january is when me and my ex started having i never had my period during that time.Then in febuary i had the most wierdest period ever.I had clear discharge and some bleeding no cramps we had that day because i didnt think i had my period.2 days p and it gets a little heavier but not as heavy as they are usually ? My period end 1 to 2 weeks and ended during that time i had a runny nose outta no where it was hot and nice out and i barely infact never get i never get runny noses i thought it may be allergies,but this lasted 2 weeks then followed bye a stomach for 3 weeks ll the time i would take 3 hour naps i thought maybe i wasnt getting enough sleep so i went to bed and 7 p.m and woke up at 5:15 and i was still tired. Usually my period comes at the beginning of the month or and the end of the month! It hasnt came for 4 months Im concerned ! Yes i took 2 pregnancy test, one on the day of my missed period and it came out neg,and i took one maybe a month ago and there was a thin faint blue line that made a positive sign,yes im under the age of 18 and im very scared to talk to my mom about this! Can someone please help me !