Bleeding

So I’m 15 and I started my period at 11 I think. So I’ve been bleeding for 4 years now and it’s still not normal. Like I’ll have it one month and then not for another 4 month and then it happens again for 2 months straight and then disappears. Anyways, I’ve been having it on time for 2 months, and I should’ve had mine, I’m 14 days late, however I’ve been noticing blood in my discharge, but that not how my period normally comes. I’ve also been cramping badly which doesn’t happen. Should I be worried? And no I am not pregnant