Hi and welcome.
So sorry you are suffering. As others have said search out neuro otologists in you neck of the woods and tell your GP you want a referral . If you don’t want to wait you can see one privately, usually without a referral (you may be asked to write a one side A4 summary of symptoms and history) it has cost me between £195-325 to see specialists privately in the UK. Have a google and look in past threads on here that mention specialists. Or tell us where you are and someone might be able to suggest a clinic . As others have said we can’t diagnose and a MAV diagnosis is always a “waste paper basket” one, not definitive but given when other things have been ruled out. I found having balance tests etc. did reassure me that nothing “sinister” was going on with my brain.
I’m surprised that since you have Migraines twice a week that you have not been offered a preventative medication for the headache (the treatment for MAV is also migraine preventation meds) such as propanalol, pizotifen or amitriptyline. Most GP’s will treat actual headaches, even if they are stumped about all the other dizzy and balance associated symptoms. Do you take an abortive for your headaches such as sumitriptan? are you over using NSAID’s or the like to control the pain and getting rebound headaches?
I think you need to go back to your GP and lay it on really thickly about how much it is all impacting your life and push for a referral and ask to start a migraine prevention med. I sympathise with not being believed, I’ve had various GP’s tell me over the years that it was “all in my head” and I was also misdiagnosed with Menieres by ENT’s and the Neuro at a specialist “headache clinic” told me that dizziness with a migraine headache could only be episodic, part of the prodrome, not 24/7 and my symptoms were “something else”. However, there are good doctors out there, I was properly diagnosed and treated by a neuro otologist.
I’ve been taking pizotifen for almost 2 years now building up from a really low dose to 4.5mg per day and am so much better, not 100% but pretty functional . Whilst you wait for a referral I’d try a simple migraine diet such as the 6C’s that cut out most migraine triggers, if you don’t want to do a diet or know that food andsome alcohols don’t reallyseem to trigger you, I’d at least cut out caffeine. Keep a diary to see if you can identify any triggers e.g. thundery weather, strip lights, loud clattering in restaurant, hormones, playing on a PC or console for too long, stress etc. Also, be fairly strict with sleep - try to go to bed and get up at the same(ish) time everyday. Be kind to yourself, take things easy and try not to stress about stuff, don’t feel guilty about resting if you need to or swerving invites when you feel bad.
You can improve, get a referral and start on a treatment plan. Have a google and pick a doctor who talks about MAV or vestibular neuritis in their blurb. You may need to be pushy with your GP and if you get knocked back, see another one from the practice as they may be more amenable. Read some of the Success Stories on here.