I am at my wits end. How to get diagnosis in the UK?

My normal blood pressure has always been lowish, around 100-110 by 70, but nothing dramatic.

I had some strange heart-related issues after I gave birth more than a decade ago, but since around 2019 it is getting progressively worse. I am broken at this point, disabled on more days than not.

I don't have a classic drop of BP when I stand for a few minutes, instead, after any minor illness ( can be barely noticeable sore throat) my BP plummets to 85/60 or sometimes even lower. The difference is very narrow, sometimes 23-26, pulse is a bit elevated, around 100, normal for me used to be 75. Extreme fatigue, I can't even work in front of my PC and read, not to mention other daily activities or driving. I became totally unreliable as a worker.

It won't budge if I take coffee, methyphenidate (ADHD meds), or salt, compression socks, anything. Only heart rate spikes to 130 or 140.

God forbid any meds lower blood pressure. I had systemic effects from eyedrops that should not cause systemic effects when BP dropped below 70 systolic.

If I have the flu, the recovery takes 3-4 months, a minor sore throat, or after a migraine, it takes a week or two to recover and get functional again. It can be triggered by a lack of sleep sometimes. But I guess viral infections and migraines are the worst.

This also left my hemiplegic migraines unmanaged, because I can't take triptans and a lot of other meds that lower blood pressure, which can literally send me unconscious. The worst episode was at 55/35, and I could barely stay conscious. Measured on two devices.

When I mentioned dysautonomia in A&E when I was there with acute migraine, they acknowledged it might be, but said, "not in this country".

I finally have the neurology appointment regarding migraines that are getting totally out of control, and I want to bring the BP issue to their attention, as my GP has ignored this for many years.

I don't know what to do, as I can't work, I can't drive, I can't function and be a normal partner and mother, I am just deteriorating, and everyone around treats me as a liar despite having photos of BP readings.