Me and my boyfriend had unprotected sex when i was on my period and then i got my period again in the same month could i be prenant?

Probably not, but...: Unprotected sex can lead to pregnancy, and all vaginal bleeding is not a period. Take a pregnancy test if you are unsure or miss a period.

Very unlikely: If you had intercourse during the early part of your period, like the first or second day, and then a normal period followed at a normal interval of time, then you did not become pregnant. If you want to be absolutely sure use a home pregnancy test. This is a good time to see your doc for a reliable method of birth control and protection from as well as testing for sexually transmitted infection.