I am new on this site as well. I logged on and saw your message and wanted to send my sympathy and understanding. I am 51 and have had migraines since I was 20 and I know it is rough seeing doctors and trying to make them understand your problem. I am currently disabled due to the frequency of the migraines. I worked up until 5 years ago and I could no longer hold down a job because I became so undependable.
As far as you asking about the doctors and nurses, how to make them understand your not "drug seeking", well you're right, that is a hard one. I worked at a medical facility for one year and what I was told by some of the doctors and nurses was that migraines and back aches were their 2 worse "excuses" for people seeking drugs at the ER and the doctor's office. I told them that made it really difficult for the people that really needed help, especially when it comes down to having to go to the ER because the pain can be so unbareable and you're dehydrated. I sometimes think in my life time I'll never see the day that as a whole, the nurses and doctors (not all of them, but a lot of them) will ever understand and will always treat pain that is hard to diagnose or see.
Every individual's migraines are not exactly the same, as you are aware of by now. My neuroligist and the other one's in my past are still not sure exactly why we or I should say I, have the migraines. It must be bad to have both migraines and seizures. My doctor said a lot of people that have one of them, get the other. They have tried several seizure medicines to help with my migraines. So far, nothing really helps to prevent them, except for me to watch and be careful of everything I do, i.e. different foods (especially no msg), stay away from stress, sleep right (not too much or too little), the list goes on and on. Sometimes the slightest things will trigger one. I'm sure you've figured your "triggers" out. Maybe you can ask around and find a doctor that has has a better understanding of migraines/seizures and with more empathy.
You also said you couldn't take Beta Blockers because you are alergic to them. Imitrex, Maxalt, etc. are a different type drug (sumatriptan), so you are allergic to them too? I use Imitrex and it helps me a lot, but at times, not at all. Before sumatriptan drugs came out, I was in the ER all the time, now I rarely go.
I am sorry for your pain and I will pray for relief. All you can do as far as the doctors, is try to get them to understand the pain you are in. Take care and God bless you!