redlo, I'm on Forteo (third year). My bone density was slower than yours to respond. Forteo gets busy reconstructing cartilage which doesn't appear on dexa. My second year dexa was better.
There are a few things to consider. Your weakest areas in in the trabecular bone in the spine and in the femur. Forteo is thought to work better in trabecular bone than any other medication including Tymlos. If you had TBS it would probably reflect reduced fracture risk because it attempts to calculate the microarchitecture in trabecular bone.
Tymlos would be effective and would get all the credit for the hard work Forteo has done, but you may not have horrible side effects with Tymlos. That "might" alone would make it worth trying Tymlos.
Strangely some of these medications aren't effective for some people. So there is that possibility.
One concern is that you've been on the medication and you are still having side effects. Sometimes Forteo serves as a warning that we should test to see if there are secondary causes of osteoporosis--namely kidney disease, or hyperparathyroidism. It could be a simple problem with too much calcium or too much D3.
I love that they are referencing the bone markers that they didn't want to order.
Bone markers have proven reliable in studies as evidence that bone repair and increase will show in increased bone density on dexa. I don't know how your doctor's method of assessment.
Have you been tracking calcium, magnesium, phosphorus, and pth.
I should lay low and let people who have switched from Forteo to Tymlos. I haven't. I'll never stop taking Forteo willingly.