M21 - I too have been having crazy bleeds and my dr explained it can be a sign of perimenopause but not necessarily. If you're menopausal or your ovaries are starting to run out of eggs, your brain starts producing more and more FSH (which is the chemical which triggers ovulation) so high levels of that in your blood can indicate menopause, or like N2L pointed out, a low ovarian reserve.

BUT: it is also possible to get the heavy bleeds and the weird perimenopause symptoms for other reasons too. I think your dr has probably referred you for an ultrasound to make sure there are no fibroids or issues like that (to explain the heavy bleeding) and i suspect they will do blood tests next. As far as i know they can't diagnose perimenopause based on an US. I've had the crazy bleeding too but in my case my FSH levels are still in the normal range, and it has to do with the pituitary axis shutting down. Sometimes this can happen if you're not eating enough, if you're stressed, if you've had surgery, if you've had an accident or had some bodily trauma. If this is the case it doesn't necessarily mean you're menopausal.

Fully understand what you mean with the heavy bleeds, it is literally like a tap, and very difficult to manage when it comes on so suddenly like that. I had a couple of periods that were so bad I was going through a super tampon and a maternity pad in an hour. My dr gave me a medication called Cyclokapron which has some sort of clotting action and it works really well to slow the bleeding, so if you're having problems managing the heaviness, talk to your dr about whether it might be helpful for you too (not sure how it would go with the TTC side of things).

Depending on what your dr says, if you have any further concerns at all, don't be afraid to ask for a referral to a fertility specialist.