Are you eating food with MSG in it? Most restaurants add it to everything. Most processed foods have it too. This can cause triggering paresthesias. Histamine releasing foods or foods with lots of histamine in them also may trigger PN type symptoms.
Do you have times with less or no symptoms? Keeping a journal may help you isolate a food problem. Nightshade veggies (peppers, tomato, potatoes) can trigger tingling.

People come here mostly when they are falling thru the medical system's cracks. Dissatisfaction with doctors is very common here. It is therefore time to consider some DNA testing. Our Bipolar forum has just started reporting that they are now being tested for DNA mutations. People here do get this testing too, because I encourage this. Janie has had this testing and found out some very important information about herself, which is not common. Doctors however do not still encourage their PN patients to have this testing, which is really quite a shame. It appears that the doctors treating bipolar have just had medical continuing education and this has not reached others, yet.

If you have not done so yet, I strongly encourage you to have the testing. Janie can share her posts and information for you here. The most common mutation is MTHFR which up to 40% of people in US have. Her major mutation is with biotin, which is much more rare than that. So that her supplement stack would be different thatn most of the other posters here.

The DNA testing like (23and Me and others) is not so expensive now and can be done. Having equal presentation on left and right sides of the body suggests a global problem and not specific to compressive triggers like your lower back. Charcot Marie Tooth (CMT) is a genetic PN error which there is no treatment for as yet. Testing for it is still very expensive however. If a doctor suspects this, he/she will often stop other testing.

There are exceptions to equal left right presentations.
Your B12 should be above 400pg/ml...but labs still report lower numbers as "normal" so you need to check your results on your blood work. If you took fluoroquinolone antibiotics, or Flagyl in the past, or statins for cholesterol those damage nerves even after stopping the drugs. So exposure to those and some other drugs continuing, will thwart any efforts you choose to help with healing.

There are over a hundred causes of PN, and having some information pointing to a specific cause, helps tailor what you
can do for yourself.

Your activities and job can point to PN issues. Constant vibrations (tools and machines), exposure to solvents, excessive exercise routines can contribute to nerve pain/discomfort).
Excessive sugar consumption can lead to pre-diabetes, with can have PN symptoms too.

Lots to think about therefore.