Is a slow blood flow during period normal when period is usually heavy?

Not to be gross but when i get my period it usually starts out heavy and stays heavy for like three days and stops on the fifth. yesterday i started to bleed but it was really little only when i wiped i can see tints of it. today it got aliitle heavier but its not heavy enough like normal. I was just wondering if anyone experience this might know why this can happen. Im 18 so it ain't menopause. please help me. Could it be pregnancy but im not sure of that.