I have had irregular periods now for the past 5 years. Mainly down to gaining a lot of weight and having the depo injection 5 years ago. I have recently lost almost 2 stone and my periods have become a little more regular, but still not fully. DH and I have been trying to conceive baby #2 for almost 5 years also (after the first depo injection had wore off after 3 months). There's been no luck, but I don't think that this is relievent?
I missed a period last month, which is quite normal for me. I started a period 3 days ago now and it is incredibly heavy. I am going through super plus tampons + a pad every 1 and a half to two hours. I am waking in the night to change or to clean because I have leaked. (TMI alert) It contains quite a lot of stringy black blood and clots. I can feel blood pouring out of me while on the loo. Cringe Sorry!! 
I am becoming increasingly worried. Surely this isn't normal? It can't be, can it?
It's showing no signs of calming down, if fact at times it feels worse.
Any advice would be really appreciated. Thank you & I do apologise for the explicit detail.