HI, I am 17 years old and I had unprotected sex about 11 weeks ago, and 6 weeks after I noticed my belly starting to get bigger and rounder which is weird because I have always been very thin and I didn't gain any wieght so I took a pregnancy test and it came out negative and I have had my period, it has been very light and only last a few days but that is very normal for me, but I keep experiencing pregnancy symptoms and my belly is still big, Could I be pregnant?