@roseincalifornia, the ~73% increase in P1NP indicates that Tymlos is working as expected; and that P1NP would have been even higher earlier (2-6mo). This level of of response is associated with meaningful gains in bone mineral density. As you pointed out, newly formed bone (osteoid) can take months to become fully mineralized and show up as measurable gains on DXA. I've read that beyond that, secondary mineralization continues for up to about 30 months.

I was diagnosed with osteoporosis at 59, with slightly worse T-scores than yours. I've since completed Forteo treatment and am now in the maintenance phase. My progress is in the table here: https://connect.mayoclinic.org/discussion/forteo-teriparatide-followed-by-hrt-my-experience/
As you can see, the BMD gains were slow at first and accumulated gradually over time and ultimately became quite significant.

I know all the uncertainty can make us anxious while waiting for the next scan. But your P!NP response is an encouraging sign and hopefully your upcoming DXA will begin to reflect that progress.