Heavy Period

My period was late by about a month and a half. I had both blood and urine tested for pregnancy. Both negative. My period just started yesterday but it's so uncomfortable and heavy. I'm bleeding through my tampons and soaking through the pad underneath. It's disgusting. My periods are irregular but they have never been like this. Never this much blood. I'm trying not to panic. Is this normal or should I go get checked out? TIA