What's the best forms of exercise to increase bone density?

Walking is fine. Also, certain types of Pilates, which involve resistance training.

Over the years, with multiple concerns, (for physical and mental) the common advice is simple: MOVE!
The worst is sedentary lifestyle; the best is resistance exercise.
May your numbers improve!

This link might be helpful in fine tuning yoga exercises for pelvis/spine/transverse-abdominal muscle connection:
https://yogauonline.com/pose-library/change-your-perspective-of-pelvic-tilting-how-the-transversus-abdominis-can-help/

Check out stump squats :

I can only comment from a personal level. I have been reading all the comments about stomping and jumping, and I must say that I am very confused by it all. I was a dance instructor ( specialty in tap) and certified aerobic instructor ( high impact and step) I taught for 30 years. You would think I’d have strong bones- think again. I was diagnosed with osteopenia in my 50’s and full osteoporosis in my early 60’s. I have been active most of my life, but heredity rules. I think that if you have no family history of osteoarthritis, you’ve got a better shot at keeping your bones strong through exercise , otherwise I’m not so sure.

This lady has 2 sets of high impact training for osteoporosis, about 20-25 mim each. I actually followed and did for about 10 days until my knees complained. the gentle ones I found that's easier on knees are stomping either from sit to stand or side to side, and heel drop. now I'm backing off a bit from the jumping Jack's and hopping to keep my knees happy

Please remember that exercise is only one variable in maintaining healthy bones. For sure genetics trump it all.

@reillyg1013 Really appreciate your reply and sharing of your personal story! This has a powerful implication that genetics often has an upper hand. It is pitiful that science is not all clear about, or it's very hard to do a perfect study on epigenetic influences on disorder such as osteoporosis. In my case i probablly had some genetic traits since my maternal grandma and greatgrandma were both extremely petite. Althougn they never were diagnosed having op, i suspect they did have it to some degree and they ovbiously had sarcopenia. They both lived a relative healthy long life toward 90s without fractures, which is my goal, long life or not.

In any case, most of us with op have a disorder, either we didn't build our max bone mass when young and/or lost too much too quickly as we age. We need help, lots of self study and learn from each other to save our bones.

I'm curious and would like to know, you don't have to answer though if inappropriate since this is a public forum, whats your nutrition like in bone building years (childhood thru mid 20s), as well as after perimenauposal?

I agrée. I have been going to the gym since my 30s using weights to build up my legs, the machines on the circuit that focused on the legs, etc. and still I have Osteoporosis. I still lift weights. But there is Osteoporosis on sides of the family.
So heredity is key.

Thank you for your query. I believe our nutrition was relatively on the healthy side. I did not share my mother’s love for liver & onions, but we basically ate a Mediterranean diet, especially since my father was born in Italy, and beans and greens were part of our weekly menu. My mother was very strict about our eating habits, there was no such thing as snacks and soda as we grew up. As an adult, I was very conscious of my eating habits, first time I joined WW, I was 19 years old.
I too am petite, but I also have asthma since childhood, that’s why I began dancing in the first place, Dr. said it would help my lungs. Until recently, I always ate plenty of fruits & veggies, but recently being diagnosed as pre diabetic, I pretty much have given up those things I love.
Again, I will refer to genetics, maternal grandparents and mother and sister - all diabetics. My mother had her first hip replacement at 54, followed by 2 knees and then 2 more hips.
I don’t think people realize that we can only do the best with what we are dealt.