Definitely take pictures of the clots. Are they bigger than a 10p coin? I'd go to your GP and ask for tranexamic acid, (they can give you more and at a higher dose) it can massively reduce heavy bleeding. Make sure you take it consistently 2 every 12 hours normally, for days as it takes a few days to work. If that doesn't work after a while, try northisterone as that can also work.
Also ask your GP to refer you for a transvaginal scan and a pelvic scan, that can check if you have a fibroids etc.
There are some different treatments for fibroids if you have them, I'd be happy to say more on.
Also look into the mirena coil or the pill, sometimes the mini-pill is better. It uses progesterone to thin your uterus lining so there's less bleeding, cramps, pain as well. The mirena often works better as it is localised.
Insertion can be made way easier with the right tools. Paracetamol, ibuprofen 1h before, licodaine injection, numbing gel etc.
Try using a pad and period pants, you can get some from M&S, Tesco I think etc. Also incontinence pads are often thicker in my experience so use those.