I got my period two days late (so I got it on the 8th) but I had sex just the day before and he came in me like 2 or 3 times. I spotted for a day and then got a pretty heavy period for 3 days. And now I'm spotting again.. what can be the case?

Has this happened before from sex

Infection perhaps,

A check up with you GYN.

No this has never happened before. Me and my fiancée do want a baby. Is there any chance I could be pregnant?

Slight chance of pregnancy, but having sex around the time of your period can sometimes throw it off a bit. It is not unusual for a period to be off by a few days here and there. See what happens when your period is due next month.