RE: Fighting Self-Pity and Battling Invisible Illnesses...

Have you tried medicinal cannabis?
It may not help on the fatigue side of things or mental clarity, but could certainly alleviate some of the other symptoms you've described, stimulate appetite, prevent migraines, reduce outbreaks or seizures, etc...
I know many people who use cannabis medicinally for the ailments listed above, and swear by it as the only thing that has helped their conditions when the medical establishment was unable to properly diagnose or treat their conditions effectively.
Just a suggestion, definitely something to look into if you haven't gone there yet. I'm a licenced user in Canada where it is expected to be fully legalized next year, but I know NY is still kinda tight on that sh-t, even medical use, unlike Colorado or California.