Welcome to NeuroTalk:

Your TSH is considered today to be borderline. Newer ranges end at 3.0, but many doctors still cling to the old range. Hypothyroidism is a cause of PN. That is how mine started 30 yrs ago. I'd get a more aggressive opinion on your thyroid. In my case I had a radioactive uptake scan showing that the gland was damaged. Treatment with only 75mcg of levothyroxine was a huge help. I still have some 10% remaining numbness in 2 toes, but I had a very good response to treatment.
I keep my TSH between 1.5 and 2 now.

The B12 is a bit low and you can raise that up yourself with oral methylcobalamin.
Here is my B12 informational thread:

http://neurotalk.psychcentral.com/thread85103.html

I would also get tested for Vit D. Low D is showing up now in many people with hard to diagnose conditions and who have chronic pain.

Vit D information:
http://neurotalk.psychcentral.com/thread92116.html

Do you know what your A1C results are? Hidden insulin resistance and prediabetes, can start the neuropathic process long before frank diabetes. Sometimes fasting morning glucose is normal or even low, when this starts. At that time damage can be happening to your nerves.

You will also want to look at current and past drug use.
Statins for cholesterol cause neuropathy in some people. So do many antibiotics.

Drugs that can cause neuropathy:
http://neurotalk.psychcentral.com/thread122889.html

You will need to look at your environment for hidden toxins. Arsenic in well water, heavy metals somewhere like lead, mercury or thallium or cadmium, solvent exposure from hobbies or job, (various art or printing activities)
using dry cleaning services may expose you to solvents too.
Pesticides in farming and gardening.
There are many other things as well... including autoimmune problems which need aggressive testing to find the culprit.

Unfortunately, but true, is that many people with PN have to become a detective of sorts, in order to find their trigger, and help improve their lives. Doctors today only do so much and that is not alot.