Unprotected sex the day before my period my period came next day it lasted 3 days then 12 days later i had this stringy red discharge can i be pregn?

Not likely: If period came at expected time it is unlikely you conceived. Bleeding later is likely associated with ovulation.However, miracles do happen, and unprotected sex is always a gamble. If you were "trying" or "hoping" to get pregnant, all you would need to do is have unprotected sex. I would certainly do a pregnancy test 2 weeks after the sex to check. It will almost always be positive if you are.