I can share my history which may or may not be relevant. I was severely anorexic from ages 13-18. I was diagnosed with osteoporosis in my spine and osteopoenia in my hips at age 17 in 2004. From roughly October '04 to April '05, I went from 93 lbs to 115. I’ve since stayed 115-122 lbs (I’m 5’6") and in Feb. '19, my bone density scan indicated a 10% improvement in bone density. I’m back to normal hips and an osteopoenic spine. (I’m 32). The improvement for me was from (1) maintaining a healthy weight for a very long period of time and (2) birth control pills. I lift weights occasionally - far less than I should.
Bisphosphonate meds seemed like a good solution 10 ish years ago but more recent studies have shown mixed results for the long term; I think you’re right to avoid them.
Cliff Rosen is one of the leading researchers about osteoporosis in the country. He is based in Maine (or was 10 years ago). He’s who NASA calls to ask what will happen to astronauts’ bones. He does research and has a medical practice in Bangor, ME (or used to). So if you were going to get an outside consult, I’d try to get your records sent to him.
Anyway, if I were you I’d lift some weights and maybe try to gain some weight (as unappealing as that might be).
Keep us updated, please. Good luck.