I don't think 300mg of alpha lipoic is not really enough. If you use alpha form you need to take at least 600mg a day. All the studies were done with high doses.

If you use r-lipoic, 100mg a day is enough for most people.
R-lipoic has become easily available now, in the past 2 yrs or so.
Still too new to appear in studies however.

Alpha contains an inactive isomer, which necessitates a higher dose to get enough of the active one. It also tends to cost more money.

All PNers should have testing for B12 levels and Vit D. I think these are the most critical.

The trio of Metanx
methyl B12
P5P pyridoxal
methyl folate

Are helpful for nerve regeneration.