Had sex 3 days before my period. tested the day of my period and got a (+). few days had slight burning in stomach. no other symptoms. still pregnant?

Probably: Pregnancy almost immediately slows down the movement of digested food through the bowel and may cause reflux (heartbur), one of the more common complaints of pregnant women. Loss of a pregnancy usually involves vaginal bleeding. The best way to check for a healthy pregnancy is to measure beta-HCG levels in a blood test 48-60 hours apart. That number will usually double in normal pregnancy