I definitely feel your pain, and I am SO sorry. I get lots of migraines with pregnancies. I know it's hormonally related since I also get them with my cycle, but I'm prone to them anyway. It just doesn't take much for me to get them normally, and when I'm pregnant it's ridiculous how easy it is. I just pay very close attention to what triggers them, although, there are a few that are unavoidable. I have to stay super super hydrated, eat very often, stay out of the heat, not exercise to vigorously, avoid food triggers (for me, acidic foods like dark chocolate are huge triggers), and hope for the best. Also, the worst migraines I've gotten with this pregnancy are sinus related. I got a cold that gave me some serious congestion, and I had a migraine for three days (it's really unusual for mine to last longer than a day!). Anyway, staying on top of any possible congestion by staying hydrated and using the Neti pot has really helped. My midwife suggested taking Marshmallow Root as an herbal remedy, and I was surprised that it really helped with my migraine (that's what finally ended the three days of agony). She said she's had lots of positive feedback with her clients that are migraine sufferers. So maybe give that a try? It's pretty cheap, so no loss if it doesn't work!
So basically, my suggestion is stay hydrated!! I aim for like 6-8 16oz glasses of water daily. That keeps the congestion away for me and keeps me from getting overtired, overheated, etc, which all lead to migraines :). Also, maybe try the Marshmallow root?
I sure hope you can get some relief soon!!!