I just wanted to leave an update for anyone who might come across this thread in the future.

In about 6 weeks, I brought my B12 level up from 'less than 150' to 1300, which is above normal, but not dangerous. I took 2500 mcg Jarrow methyl B12 twice a day sublingually. I put a pill under my tongue and let it sit there and slowly dissolve over 60-90 minutes. I made sure not to swallow it, just let it sit under my tongue.

I only received one B12 shot from the doctor (cyanocobalamin). I didn't follow up with the shots because I preferred to get methyl B12 based on my research on B12 deficiency.

The numbness and tingling I was experiencing in my legs and arms is now pretty much gone.

My legs are still very weak, but it turns out I have another medical issue that is most likely causing that. I'll still take my B12, but I'm moving on to treating this other issue.

If you are recently diagnosed with B12 deficiency, I recommend you get the same methyl B12 form that I did. At least you know that it normalized my blood level after less than 6 weeks. For your reference, my physicians also tested me for folate, lyme disease, thyroid, and cortisol. All were normal, but you may want to request these tests as well. Take care!