Hi there,
I totally sympathise, migraines are HORRIBLE. I was on beta blockers for them before I got pg but had to stop taking them. I had trouble with them this pg up to about 15 weeks. The only thing that I found gave any relief was co-codamol which I got prescribed by the out of hrs dr & my consultant said they're fine to take. My consultant did look at putting me on a drug called labetalol which is used for high BP in pg, but it was decided that because I have very low BP the drug would make me feel really poorly as it would make my BP even lower. If the migraines really are causing you that much trouble then you could talk to your gp about that or ask your MW if you could be referred to a specialist.
Really hope they improve soon xx