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

Sophie, both Forteo and Tymlos slow progression. They have the advantage of increasing bone mass more powerfully than the bisphosphonates. Current thinking is to take the bone building drugs first because bisphosphonates (Fosamax) blunt the effect of the anabolic drugs (Forteo, Tymlos). There is some buzz about combination therapy.
You might contact your physicians' offices and ask them to consider anabolic drugs. I would specify Forteo (windyshores might say Tymlos).
If you don't have your bone marker results, you might ask for them.
Our bones break down so that they can be rebuilt to protect against fracture according to our current activity. The new spicula (the slender bones called trabecular bone) in the center of the bone realigns itself (anisotrophy) so as to provide the greatest strength for the angle of impact. If you are jumping out of airplanes, or skipping rope it prepares the bone for that particular angle. The bisphosphonate stop that process by preserving old bone.
It may be that Fosamax is the best drug for you right now. You might want to see an endocrinologist who specializes in osteoporosis. But be assured that those powerful drugs are waiting for you whenever you need them.

Thank you for your elaborate&helpful reply! I understand... Luckily I have an upcoming appointment with my endocrinologist the coming week. I will mention Forteo and see how he reacts... In the meantime, I'm keeping up with my exercise routine (walking every day religiously), eating healthy and minimizing smoking (this one is the hardest for me, I have to admit). I was thinking about supplements, but not sure if I should even start them at this point.

I know how scary this all seems. My T score in my spine is -4.6 it dropped 13 %. I was referred to an endocrinologist and was told right away to start Evenity.
I did all possible labs to see if there was an underlying issue. Nothing all labs came back normal except my CTX was high at 934 which is a bone resorption marker. Still waiting for my N1 NP marker.
Never had a fracture. I have worked out all my life with weights ect. I'm very active I walk & jog. I eat mostly a plant base diet and I'm beginning to think that maybe I do not eat enough protein. 0.8 × your body weight and its best to consume at least 30g per meal and that's being conservative.
I am not even a month in from starting Evenity.
You should start in with taking a bone Anabolic medication. Such as Evenity, Forteo or Tymlos . These build up bone and prevent further breakdown. The other meds are Bisphosphonates which reduce the development of new osteoclast so it stops further breakdown of your bones.
I am a retired RN and have looked into many options we all have to decide what is best for ourselves.

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.

Sophie, your bone markers are calling for a bisphosphonate while your Tscore pleads for and anabolic. You might look at the difference in mechanism of action. It is good to determine a preference before seeing a physician. Then when/if they offer you a choice', there isn't further delay in treatment. I'm pretty certain you'll be ready.
I'm partial to Forteo. I'm not happy with the slow way bisphonates work or the bone they save. I don't like Prolia or Evenity, though both are easier with fewer injection.
There are youtube videos cartooned to let you see the molecular actions of the drugs, usually produced by the drug company.
If you throw out any questions, we'll get a lively discussion going in preparation for you endo.

I had a total hysterectomy when I was 40, and started on HRT estrogen patch for 50 yrs. Then had knee replacement surgery a few yrs ago and was told to go off it due to clots. This past summer @ Mayo in Rochester was found to have severe osteoporosis in the spine. Doctor wanted me begin on Evenity. After much research, I decided to delay the Evenity. I Googled HRT for osteoporosis and found in the United Kingdom and other places in Europe it was part of their treatment. The spoke of menopausal doctors and their treatment plans. I tried here in Mpls and found a doctor who was not in favor of this treatment. She finally consented and for Medicare purposes listed sleepless ness to be coded. Since I am over 60, it is not recommended. I have the lowest dose and change patch weekly. I know that it will not rebuild bone, but hopefully will maintain it. I am now enrolled in a balance class, will have OT and PT for resistance trying and stretching. I am to walk 30 mn per day. Many of my friends in their 70’s continue to stay on HRT with no side effects. Because of the flawed nurse study, doctors won’t recommend it for fear of being sued. I am angry that no additional studies have confirmed or denied this study.
So I will continue on HRT and hopefully others on this chat room will seek out answers for this hidden and common disease. Thanks for listening. How can we change attitudes of HRT in this country? Much more research must be done!!

As a person who had breast cancer fed by hormones, I have concerns about HRT for us older women. But for someone going through very early menopause, I think things are a little different.

By the way I am partial to Tymlos 🙂

Have you had your parathyroid glands checked? What is your calcium level? Have you done a 24 hour urine test? All of these tests will give you information as to why your body is losing bone density. If your parathyroid levels are off and your calcium levels are too high, your body is not absorbing calcium the way it should and that can greatly effect bone density tests. Ask your doctor!

Yes, everything is fine. Parathyroid as well as calcium levels.
It is the lack of estrogen. First years after menopause are notorious for losing bone density, as my doctor said 🙁

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 :/