Miss Lemon, sorry to tag on to this so late but I have only just read your post. I started having silent migraines (migraine aura without headache) once my oestrogen levels started to drop. To cut a very long story short, in my case, the migraine aura is caused by a combination of synthetic progesterone (all types and also Utrogestan (bio identical) if used in high doses) AND low oestrogen. Absolutely nothing else causes my migraines.
When I had the first attack, I had a Mirena coil which contains synthetic progesterone and that, together with my low oestrogen level, was enough to trigger the silent migraines. A silent migraine consists of (usually) a blind spot followed by scintillating scotoma which is a horrible shimmering, zig zag pattern that lasts for approximately 25 months before disappearing at the upper, outer sight field but no headache afterwards. I used to feel spaced out afterwards but the last time it happened I bunged on a huge blob of oestrogen gel and that aborted the attack.
I was never the least bit sensitive to my own progesterone and although I never liked periods (who does), I never had any problems with them or had any PMS symptoms, this only started when reaching the menopause. Also, I took synthetic progesterone in the pill years ago and had a Mirena coil for contraception purposes (before my oestrogen levels dropped) and although I didn't feel good on either of these forms of contraception I didn't have one single migraine.
I sought the advice of migraine expert Professor Anne MacGregor and hormone expert Professor John Studd and it would appear that during the hormone gateway, my own hormones were able to override the synthetic ones hence no migraines but as soon as my oestrogen levels dropped off, the synthetic progesterone hormones became dominant. Apparently synthetic progesterone can wreak havoc on your brain receptors which is why so many women feel terrible while taking them.
I now take 2 pumps of Oestrogel everyday, a small bead of testosterone and 7 x 100mg Utrogestan (bio identical progesterone) vaginally every 5 weeks - I cannot take any more than this. I also take DHEA, magnesium, vitamin B complex and aspirin everyday and so far, so good. I don't want to say any more than that because I don't want to tempt fate!
The important thing is to find out what causes your migraines, oestrogen or progesterone, synthetic or otherwise.
I hope my experience helps you and others reading it.