What Causes Short Menstrual Cycles With Severe Abdominal Pain?

I did dry humping with a boy. He ejaculated on me but i was in fully covering panties (not thong, more like granny panties) plus leggings. The sperm was on my leggings then he wiped it with a tissue. When i got home i changed my clothes. There was no penis in vagina intercourse. He fingered me but before he started playing with his penis at all. After he touch his penis he did not touch my vagina. After +3month after this situation i took pregnancy test and it came negative. I get period normally.its not light. I feel like its little bit shorter than usual but still bleeding heavily and stomach hurting. Could i be possibly pregnant??? Im so scared