I would really get your test results to see if you had B12 done.
It is not included in a regular testing panel, and needs to be ordered separately. Then as if that isn't enough, doctors don't always interpret the results correctly. You should be at 400 or above. So you need to press for the numerical results.

Continuing to drink with PN is problematic. I would try to stop.
here is a link to a discussion where alcohol is discussed:

http://neurotalk.psychcentral.com/thread104096.html
I would start at 300mg of Benfotiamine a day. And since you
are skirting that diabetes label, you might improve with 100mg of Lipoic acid Stabilized daily too. (Doctor's Best for both of these, and available on Amazon now.)

There is some evidence that Biotin helps with blood sugar as well. 5mg a day at a different time from the lipoic is inexpensive and worth trying. Puritan's Pride has this at very reasonable prices.