My name isXXXXX you for using Just Answer. I am happy to try and help you with your concern.
Your back issues would not be related to the other symptoms you have. If your parents or siblings had issues with their back, so will you. Back pain is the 2nd most common reason people visit the doctor, with the 1st being headaches. It would be a separate issue from your anemia and thyroid problems. There are several treatments available for back pain including medications, physical therapy/exercises, injections and in some cases surgery.
Being that your glucose is high, have the doctors given you a diagnosis of diabetes? Untreated diabetes can lead to kidney complications which can lead to anemia. If it is diabetes, the anemia should correct itself once the diabetes is treated either with diet or insulin.
Since you have a mass on your thyroid is your thyroid working properly? You should have your thyroid levels checked including blood work called a TSH & T4. People who have hypothyroidism (under active thyroid) are more likely to develop iron deficiency anemia. Regulating your thyroid to work correctly with medications should help with the anemia.
Liver disease can cause your bone marrow to stop working or work at a slower pace which can lead to anemia. Once again, once this is resolved the anemia should as well.
If you are worried about leukemia, you would have to have a bone marrow biopsy done to rule this out.
You also need to have a colonoscopy and endoscopy done to make sure you are not bleeding internally either from a tumor, polyps or tears.
If your spleen is enlarged and it basically destroys good blood cells, this can also lead to anemia. Sometimes the spleen has to be removed in order for you blood levels to return to normal.
There are some cases where you bone marrow just quits working and does not produce new blood. The treatment for that is blood transfusions or injections of growth hormones.
My suggestion to you is to see a hematologist. Take copies of all of the blood work you have had recently. They will most likely order further blood work, an ultrasound of your spleen, liver & kidneys and probably a colonoscopy/endoscopy. If they are worried about Leukemia they will order a bone marrow biposy to rule this out (and ease your mind).
I hope this has given you some ideas of what could be going on. If you have any further questions let me know. Good luck to you, hope you feel better soon. Have a wonderful day.