So sorry you are feeling so awful. I've been in your shoes, and my heavy bleeding and blood clots started at your age too.
I agree you sound like you need to see a gynocologist as soon as possible.
For me the result was uterine fibroids. I have a large fibroid in the uterine wall and I had a smaller one that was attached and in the womb. Iykwim.
The gynocologist gave me transexamic and mefenamic as suggested below. They do give some relief in the short term, so I would definitely ask. But you need a long term solution, and it's important for you to get a diagnosis.
I have had the Mirena inserted, and the first time it expelled in a large blood clot. However I didn't want to to do the road of ablation or hysterectomy at that point. I had 3 months of instant relief with the Mirena and I wanted to give it one more try.
I had a D&C (removed lining of womb), the fibroid that was external was cut and cauterized and the Mirena put back in under GA.
So far so good. I suffer from depression, but I've had no effects so far in 9 months. As the coil contains a hormone it's very likely that you won't be feeling sick and vomiting. I don't bleed at all, I get (tmi) a pink discharge after some twinges for a week.
But nothing like a week of migraine, nausea and tenderness (crying when I had to take my bra off, pushing down on my stomach and losing a clot instantly) and then 14 days of uncontrollable bleeding, crying, not sleeping etc.
Please make sure your iron levels are okay too, and get a supplement. I had to go on an iron infusion as my levels were so low.
I hope you get some answers and relief from this soon. I know how exhausting it can be. 