Hi Sir, My Name Is Poorna. Me And My Bf

hi sir,
My name is poorna. me and my bf had sex last satrday. we din have intercourse but we had anal. he ejaculated outside. my last period started nov 25 so my next one shud be probably by ths month end. but by monday(2 days after havng sex) i startd havng little bleeding which iam having till today. tz smetimes brown sometimes red in colr. and tz not a heavy bleeding only when i wipe i can see the blood. and we took the urine test two times both time t was negatve. also a ultra sound scan. could i be still pregnant. please advise me on this because we are currently not in a situation to have a baby. so please advise me on this.