Help??

Currently assuming I may possibly be pregnant.. I had my last period on time and when it stopped I had intercourse with my partner unprotected but on a brand new pill, although I think he pulled out I've been experiencing so stomach pains and been tired a lot, I've also noticed my breast being sore and looking like they are swelling (getting bigger) I'd say I'm only 3 weeks today/tomorrow and today I've been experiencing really bad Indigestion (extremely bad all day since I woke up!) which I have never really gotten before and I've even taken stuff to help it but it hasn't, is it a possibility I could be pregnant? I'm only 16, and my period is due in about 2-3 days..  I also never ever get any symptoms for my period!