Help!

At the beginning of April I had just gotten off my period and did stuff with a guy(2 days after period ended) I gave him a handjob and he fingered me. He cumed but immediately pulled up my pants. I'm only 15 and I started my period less than a year ago so it isn't very regular. After the night with the guy I was 3 months late on my period (my period had been regular-ish 2 months in a row before this) but have no other signs of pregnancy. In fact I've lost weight. My period right now is very normal but it's longer than usual. Is there a chance I could be pregnant. Please help!