I did have an endo who was an osteo specialist initially. I've moved a lot in the last few years so had to change docs a bit. I was least happy with my last endo and now I will have a new one with an appt coming up in April. I also have Hashimotos so an endo is essential for me. Originally, I believe I had all of the bone marker tests. They never came up with anything concrete except that it was not my parathyroid and it's likely genetic. Not that I buy that but I have no other leads. I've been off Forteo for years so I don't recall the exact tests they did while on it but I think they periodically did the 24 hour calcium test and alkaline phosphatase. In the last few years, my alkaline phosphatase has still been low which they are happy about as it indicates I'm not breaking down as much bone.
I think Forteo (or Tymlos) is really your best option. Build your spine back first before going on a maintenance drug. Don't be scared of it. Go for it! The psychological relief you will feel knowing you are doing all you can will be a huge weight off your shoulders (and spine!). Also, I think it's *possible* to stabilize the hips with increased walking, heel bumps, squats with weights but really, really hard to get at the spine. Wondering if you do core work?? That's good for the spine and good for balance and stability. I do 400 core reps and a 100 back lifts every morning before I get out of bed. (I know, I'm a lunatic). It has helped me tremendously in strength, posture, tone, etc.
I'm so sorry you have to wait so long. It's very stressful. Have you tried finding a rheumatologist? They also specialize in osteo so maybe that would give you additional options. If you can get in to see someone sooner, you can hopefully get them to prescribe the drug for you and if you're not happy with the doc, you'll have some time to seek out a new provider without the stress and fear of your osteo progressing.
Fingers crossed for you that you can get in a little sooner and get things rolling!