Fourpaws I'm so so sorry for what you're going through
I absolutely do NOT think you are a lost cause, I think you've been stimmed completely appallingly
Before my first two cycles I had almost undetectable AMH (1.5) - my FSH was as high as 17.6 a year ago
Long protocol is definitely not advised for low AMH women as down regulation runs the risk of over suppression and poor response - ie sleepy ovaries don't wake up properly. So short protocol is almost always recommended for anyone with low ovarian reserve
The dose of stims also sounds woefully inadequate for someone with low AMH on a conventional IVF cycle - especially on long protocol where higher doses of stims are required. 225iu is an average starting dose for someon with normal AMH, 300iu for someone with fair AMH, and for someone with very poor AMH you might do 450iu starting dose
For very poor responders you might do mild IVF, or natural modified, where the goal is to get fewer, better quality eggs - although I don't believe the NHS tends to do mild cycles
I did very well on high stims short protocol, we got a much better response than predicted. My antral follicle count before my first cycle was just 5, we got 7 eggs. My antral follicle count before my second cycle was 10, we got 17 eggs
I also took DHEA which can help ladies with low ovarian reserve
The NHS won't normally do investigations for miscarriage until you've had 3 consecutive losses, but it seems bonkers to be funding IVF without looking into your miscarriages, as if there's a simple explanation that hasn't been addressed, it could affect the outcome of this cycle. Basic thrombophilia and autoimmune tests that are done for recurrent miscarriage would be worth asking about - it could be that something as simple as a baby aspirin and some clexane could prevent further miscarriage
IVF can help you get pregnant, but won't necessarily help you to stay pregnant, unless they're giving you the right treatment
I'm so sorry you're having to go through this, it sounds like they've just plonked you in a one size fits all box. Glitter shit to you and a massive steaming pile of actual shit to them 