Do you have a LANA certified Lymphedema therapist? If you don't I am sure Mayo could help you with finding someone. LANA is Lymphedema Association of North America. These professionals are usually PTs who have special training in lymphedema and the decompression massage. I first saw a regular PT then a LANA certified therapist. Seeing someone specifically trained and experienced with lymphedema made a huge difference. She She was able to easily and painlessly break up the cording, which helped a great deal. She also taught me many skills to manage the lymphedema.
Although everyone told me the numbness was permanent, I did recover some feeling after a long time. However, I have nerve pain in the form of occasional "shocks" and intense itching in the lymphedemedtous area on my chest wall.

As for post radiation fatigue, three months isn't very long. Be patient with yourself. You've been through the wringer and you still are going through it...

It sounds counter intuitive when you're exhausted but I have found that getting some exercise, even gentle exercise, gives me energy. I have joined Zoom classes specifically for women who have had cancer treatment.
Keep asking your doctors (oncologist, surgeon, PCP...) about the fatigue.
Best wishes.