so sorry you are going through this and grappling with the difficult decisions on medications. I agree with many who have posted that you might delve deeper into the option of going on bioidentical hormones, specifically a transdermal estrogen patch and oral progesterone. If you do that along with improving your diet, increasing your weight and including targeted weight bearing and strength training exercise, you *might* be able to increase your bone density at your age. That said, if your bones are already really bad, you might also need a bone builder. The doctors you have seen have told you that it's too late for HRT and that you need a bisphosphonate but most endocrinologists are just not nuanced in the intricacies of each person's situation. They reach for bisphosphonates as an automatic first option due to insurance restrictions. They really have a limited tool kit and generally a limited scope on the disease. Most gynecologists are not well versed in menopause and are still afraid to prescribe HRT as they are stuck in the misguided recommendations of the flawed Women's Health Initiative study. You might want to consult with an expert specifically on HRT as most doctors do not understand it enough to prescribe it. The North American Menopause Society has a database of practitioners that would be knowledgeable on HRT. You're certainly not too old to go on them though I don't know if there are any contraindications in your current health situation and family history. Worth exploring with a doctor who specializes in this area. I was 63 when I went on HRT after I did 2 years of Forteo. I was at the tail end of the acceptable window so it bears a little risk but that's true of all drugs (and of doing nothing as well, it's a complicated decision). If you go on HRT, it could potentially arrest the continuation of bone loss while you explore all of your other options.

Here are a couple of websites that might be helpful in finding a practitioner in your area. One is for menopause specialists and the other is for functional medicine practitioners who might help you dig a little deeper to find out root cause.
https://portal.menopause.org/NAMS/NAMS/Directory/Menopause-Practitioner.aspx
https://www.ifm.org/find-a-practitioner/
https://www.ifm.org/find-a-practitioner/