I have been taking Lyrica and Keppra as a preventative for about
3 months now and I can tell a huge difference. Like you, I still have the migraines, but they aren't as severe and I can function with them. I don't notice any decrease in the number of headache days that I have each week/month, but the pain is much more tolerable.
the side effects eventually go away, and you can function normally (Or as close to it while having a migraine!)
hope this helps you...