That is a terrible place to miss a shot. Is your face just numb or do you look like you had a stroke? Can you move your face normally?
I missed a shot on my arm when I used to do it (don't touch it anymore) and I lost all feeling in an area about 2 inches wide and 4 inches long. It took almost 6 months to recover but I regained feeling eventually.
If you haven't already, stop using meth for awhile so your blood vessels arent constricted and start putting a hot face cloth over your face every once in awhile and see if you can bring feeling back or if you damaged some nerves.