I and my fiance had sex while i was having my period will i be able to get pregnant?

Unlikely.: When your blood is flowing your uterus is shedding the lining necessary for implantation of a fertilized egg. Therefore very unlikely, but in medicine there is a saying..."never say never.".

Maybe: Pregnancy has been documented from unprotected sex on any day of a woman's cycle, including during menses. This would be less likely if cycles are regular/predictable. Those with irregular cycles have unpredictable egg release dates. If you are lucky this time don't plan on it for the future.