"Just adding to the advice- go back to GP and insist on an ultrasound plus a referral to gynaecology. It's not just something to put up with. I'm currently under investigation for fibroids and have the same. No man would put up with this. I'd also not recommend a coil until you have had investigations to find out what's going on"
This. So, so much this.
I ended up in hospital over the summer for severe aneamia, caused by my horrendously heavy periods. I fainted and broke my wrist, so was whisked off to hospital where they realised that the iron in my blood was so low, it was a miracle I hadn't suffered a heart attack (apparently...). My cycle is 39 days of flooding, maybe 3 or 4 days break, then perhaps another 32 days of flooding. My (female) GP at the time had spent the previous 5 years telling me that it was "the menopause" and would eventually "settle down". The doctors at the hospital referred me for scans and to an obs-gynae as a result of the scans - and my uterus has (to quote the fantastic gynea I saw) "gotten itself into a bit of a pickle" because, even though I bleed heavily, not all of the lining is being shed, so over time it's built up to a level where there will never be an end in sight to it naturally. I also have ovarian cysts which don't exactly help the situation. So I had biopsies taken (just in case), and am waiting for a panel to decide if an ablation will cure it - or if I need a full hysterectomy. I don't care overly about losing my uterus (I have children who're adults now, so definitely don't want to start again!), I just want it to stop so that I can enjoy living my life again. Transemic acid didn't do anything for me, weirdly, but I was put on 30mg of progesterone daily, which has reduced the bleeding incredibly - I'm at a level now where I knew I wouldn't flood if I went on a dog walk yesterday (tampons and night time pads still being used, though, because... well, just in case I did flood, y'know? My DP thinks I've developed a phobia about bleeding... and he may well be right).
Please, OP, see another GP and insist on a referral. Because bleeding so heavily that you're afraid of doing activities designed to relax you? Is not something that, as a woman, you ought to be expected to just put up with. As the poster I quoted said, no man would put up with this if it were happening to them - so why should we be expected to?
As women, we deserve better.