Heavy flow after stopping birth control

I stopped taking birth control about 4 months ago and since then my periods have been out of whack. Spotting. Missing. Double. Now I’m having this insane heavy flow with huge clots. My anxiety of course is telling me I’m dying. Rational me is saying it’s my body regulating. I have an appointment with an OBGYN Tuesday for a vaginal ultrasound to make sure everything ok. Ease my anxiety and tell me it’s ok? Or you’ve at least been through it? Also 30/tubal ligation/2 csections if that maters.