How bad is a spine T-score of -4 ?

I'm sorry that things have been rough for you 🙁 I know very well how frustrating it can be: You do everything "just right" and the T-score is just dropping further.
Believe me, it is NOT the protein: I have been meticulous with my protein intake, all my life, making sure I get just enough animal AND plant based protein at every meal. If anyhing, there are studies that show that increased protein intake can be harmful for the bones.
Your lifestyle sounds perfectly healthy.

Just wanted to reply to your comment that protein intake is harmful for your bones. It is actually very necessary for bone as well as building muscle which is vitally important to stability particularly for those with osteoporosis. Current analysis is pointing to current RDA recommendations being too low (as is typical with RDA recommendations which are often minimal requirements to avoid disease not necessarily optimal dose recommendations to promote best health outcomes).

For all of us with osteoporosis, I think it's important to do a whole body approach incorporating best practices in exercise, nutrition and medication when necessary. It's a good idea to look at your nutrient intake to see if you are really getting your necessary daily requirements. I track my nutrition through the website cronometer.com and would highly recommend it. It is eye-opening. I have an extremely healthy diet but I am often surprised at how some nutrients fall short of of my daily requirement. By entering my food intake, I can see where I need to supplement so that I don't overdo my supplementation (or under-do!). Some might find this tedious to do but I find it easy and fun (cause I'm a bit of a nutrition nerd :). The only thing with this website that is not optimal is that their protein and fiber requirements are low, probably because they are based on current RDAs so I shoot for higher intakes. The other issue with nutrient intake is absorption so it's optimal to work on good digestion if that is an issue.

Actually, I do have a question (not related just to my situation, even though it is the case for me as well)
Why does it seem like almost all younger adults with osteoporosis have worse scores on the spine in comparisson to the hips?
I wasn't able to find any information online :/

Actually, I do have a question (not related just to my situation, even though it is the case for me as well)
Why does it seem like almost all younger adults with osteoporosis have worse scores on the spine in comparisson to the hips?
I wasn't able to find any information online :/

I have found information that states with osteoporosis the spine is impacted first (people in their 60’s , the hips become impacted later in life, more in the 80’s. I think it probably has to do with the fact that the mesenchymal area of the vertebrae of the spine is where the differentiation of cells is determined ie…how many and what will become osteoclasts (bone eaters) versus osteoblasts (bone builders). A balance needs to be established for building and keeping bone at good levels. Sometimes it’s also my understanding that within the mesenchyme the cells may become fat cells , not bone related cells at all.

You have noticed a statistical fact. The spine has more trabecular bone and is more vulnerable to early loss. Vertebral segments are shorter subject to more force that is less distributed, and more subject to movement.
Hips are more likely to lose bone over the long period of uneven impact because of slight differences in leg length. In addition, with age comes increased possibility of other affecting diseases, like cancer. In my case, radiation through the hips has altered the bone marrow affecting the bone density. Cancers of the reproductive and digestive systems often cause bone loss through radiation treatment.
Sophie, you are interested in every detail. Your curoisity is wonderful. You even researched this.

Just wanted to reply to your comment that protein intake is harmful for your bones. It is actually very necessary for bone as well as building muscle which is vitally important to stability particularly for those with osteoporosis. Current analysis is pointing to current RDA recommendations being too low (as is typical with RDA recommendations which are often minimal requirements to avoid disease not necessarily optimal dose recommendations to promote best health outcomes).

For all of us with osteoporosis, I think it's important to do a whole body approach incorporating best practices in exercise, nutrition and medication when necessary. It's a good idea to look at your nutrient intake to see if you are really getting your necessary daily requirements. I track my nutrition through the website cronometer.com and would highly recommend it. It is eye-opening. I have an extremely healthy diet but I am often surprised at how some nutrients fall short of of my daily requirement. By entering my food intake, I can see where I need to supplement so that I don't overdo my supplementation (or under-do!). Some might find this tedious to do but I find it easy and fun (cause I'm a bit of a nutrition nerd :). The only thing with this website that is not optimal is that their protein and fiber requirements are low, probably because they are based on current RDAs so I shoot for higher intakes. The other issue with nutrient intake is absorption so it's optimal to work on good digestion if that is an issue.