vmcgrantham, I'm sorry that you are having so much trouble with Forteo. You might ask your doctor if they can switch you to Tymlos. Some people are simply allergic to Forteo. It may be excess calcium that could be resolved by lowering calcium or d supplements. Is your doctor monitoring calcium levels. Are you getting bone markers so that at least you know whether the drug is working for you.
Forteo can raise levels of uric acid. You might want those levels tested because some medications that raise uric acid levels cause pseudogout.
You can raise bone density some with "natural" remedies. With your -4.5 it would be a scary risk for fracture.
One person on this site couldn't tolerate Forteo, but managed on Tymlos.
I hope your doctor can help you find some answers.