Ok im 15 years old and i've been having sex for about 8 months or so...And i've always had an irregular period since i've hit puberty, before my last period everything was going normal and my period wasnt irregular...My last period came 2 months late, but everytime I t0ok a hpt to check if I was pregnant it always said negative, I never get any of the symptoms of being pregnant, but i've been gaining alot of weight, even though I go to the gym everyday and work out, I had sex 2 weeks before my last period came...And now my period is late again, I heard from my friends mom that having sex can also slow down your menstrual cycle, is this true!?!? I just want to make sure that im not pregnant.Somebody help me please!!! Thank you!!!!! :-* oh yea and i've never had unprotected sex...But during march I think the condom slipped off when I was having sex with my bf, but my bf said it didnt...Im worried...Please relpy!!! And help me!!