maybe or maybe not

Alright this maybe a very stupid question but is it possible to get pregnant and still bleed? I have unprotected sex on the 22nd and was suppose to get my period that Tuesday the 28th but it came the 26th and it's been super light which is weird for me because I always have super heavy periods for about five days and then it's nothing but lately it's been three days of light periods and yeah is I possible I am pregnant or is there any reason my period would change so drastic? Just super concerned at this point. Any advice?