I don't think that you're overreacting. I suspect that you have significant anemia from blood loss. You probably need emergency attention. I would go to an emergency room and at least get your hemoglobin checked.
If you are significantly anemic, you may need a blood transfusion and then a D&C.
If your blood count is OK, at least you can get an evaluation and possibly get started on some hormone pills that will control your bleeding.
It's difficult to know for sure. Feeling shaky, sweating or cold sound like symptoms of marked blood loss. A simple blood test plus testing your pulse and blood pressure will tell.
If you feel light headed when you stand up, I would not delay.
I would bring a toothbrush.
If you feel light headed when you stand up, and it lasts more than about 5 seconds, I would call an ambulance. Otherwise a taxi should suffice.
Thank you for your payment and rating and good luck!