I am 13 years in and migraine workup for about 2 years which spawned an MEB, so I can understand the stress, I think. Even with the 50% DoD and 100% VA finding I got, the stress is still strong.
My recommendation:
Make sure neuro documents frequency and severity of migraines. Most recommend a migraine diary to help this out. What days your migraines slowed you down, which ones forced you to stop, and which ones layed you out. Frequency of abortive medications used. Consider going to the PA for all the various ills you have been ignoring, some may need a specialist to fully develop a claim. Consider going to BH, most I know have things they should have addressed long ago but didn't for fear of their career. When you see the VA to list your conditions, just list everything that's been bothering you starting at the head and going to the feet, they'll sort it out was my experience.
Once the MEB is started, you will be eligible for all the WTU services, so I recommend going down there and finding out their schedules for classes. OWF is a good program so you can get a internship. Voc Rehab can also set you up with work trials. These are good ways to test out work. The ADA protects you in the non-military a bit. You don't have to disclose your disabilities, they can't ask you about them and they have to give you reasonable accomidations to help you be productive (including a certain amount of non-paid leave). So while you likely feel unable to be productive right now, there are places that can work with it better than the military can. This stuff helped with the stress more than the PEB/VA findings.
Migraines makes me wonder.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3094670/ is an interesting read IMO. I would be very concerned about the seizures being tracked and treated. At any rate, even though migraines maxes out at 50%, there are cases where migraines are so severe there is no real option of working. VA can bump you to 100% rating if you have such a case. Social Security Disability Insurance will add to that.
There is a chance you can fight the MEB, but from your story I don't see a route to that, or the wisdom.