@dukemayo and @hmbglr do you have an endocrinologist? Primary care doctors tend to prescribe Fosamax or maybe Prolia first but endocrinologists often prescribe Forteo, Tymlos or Evenity first, especially for more serious osteoporosis. @hmbglr with a -4.0 it would seem that you might talk to an endocrinologist about starting with an anabolic, one of the three I just listed.

For more info, Keith McCormick's book "Great Bones" or Dr. Ben Leder's video "Combining and Sequential Approaches to Osteoporosis" on YouTube are my favorite resources. Leder has another video on there too. He is an endo at MGH in Boston and does a lot of research.

Bisphosphonates like Fosamax should only be taken 3-5 years, I have been told. It is good to save them to "lock in gains" after the bone builders, according to my doctor. Even now, after Tymlos and Evenity, I am thinking about how to stretch that 3-5 years over 20 years! Though with bisphosphonates at the end of treatment, we can take some drug holidays.

I hope you find a good path!