Old thread, I know, but I'm curious. How did the beer turn out in the end?
I've had high gravity beers take ages - 3+ months - to carbonate, but once the get there, they turn out quite nicely.
Before you try anythingelse, you must sparge. It's practically free, and your results will sky-rocket. If you BIAB, just hoist the bag up a bit, and pour correctly heated water over it. You are so close! Just go for it!