I'm sorry you're going through this.
I feel like most of these suggestions might be obvious things you've tried, but is there any chance upping your Wellbutrin could help a little? Also, have you tried asking your pharmacy if they can order the other manufacturer for you, or considered calling other pharmacies to see if any carry the manufacturer that works best for you? I did this once with another med, and they didn't mind.

Have you ever seen a medical doctor for your migraines specifically?