Unprotected intercourse, my period is 4 days late, I feel pain in my abdomen

Hi. So i had an intercourse , unprotected one with my boyfriend on nov 7. I had regular periods after that in nov, dec and jan. But in feb m still waiting. Its almost 4 days late now. Also last month i had a heavy period with much pain. And since last 3 days m feeling a pain in my abdomen. Please help. I m 20. What could it be? Pregnancy or miscarriage?