For what it's worth (recognizing that everyone's experience is different), I am almost 20 months in and am continuing to make significant gains, albeit gradually. If I was feeling about 70% at the nine-month mark, I'm now about 80-85%. Which might not seem like a huge gain, but I am doing so much better than I was -- each of those percentile gains has improved my quality of life. I now feel pretty decent much of the time.

Hang in there, be patient and don't get discouraged. Keep being smart about your recovery and "do the do's" that Mark and others on this site recommend. Rest, nutrition, and avoiding overexertion / overstimulation are key.