Am l pregnant (l had 2 days after my periods and my cycle is 31 days long)?

my cycle is 31 days,my periods take 7 days and for the past 4 months have always come on the 17th day.my last periods started on 18 th october,2 days after my periods(ie 27th october) l had with my fience.2 days later on the 29 of october,l felt dizzy,powerless and had a black out. l have felt like that on 2 other separate days.are these signs of pregnancy,could it be that am pregnant?