There is some dissent about whether dxa should be done after the first year of bisphosphonates. The process is gradual since the drug works by accumulating bone. I would expect to maintain BMD, and not be discouraged if there were little change or even a slight lowering of BMD.. The rate of loss compared to prior years should improve. But that rate isn't calcuable without the prior years dxas. At three years you should expect gains.
Even so, I hope your gains are evident.
And I'm glad your medical provider is monitoring progress.