I had unprotected sex on the last day of my period could i be pregnant ? my periods are regular now .

It's possible: but not likely,especially with regular periods. It all depends when you ovulate.

Unprotected: 1 in 4 normal couples conceive each cycle. Have you had a normal periods since having unprotected intercourse? Have you done a pregnancy test? If your periods are normal then you are probably not pregnant, but, seeing your provider to obtain appropriate contraception should be a top priority.