I'm so sorry she's still feeling bad. I would call the clinic and see if they can get her in sooner. If not, see about a higher gabapentin dose. That's a pretty low dose for a dog her size. Our Wyatt is at 400 mg 3x daily and he is 75 pounds. That dose is just for daily pain control, hers might be able to go even higher because it's acute pain. I would think that spreading it out to 3x daily at a higher dose would be more helpful but ask your vet asap.

Is the rehab team working in the same clinic as the orthopedic vet? If so perhaps they can see her sooner and put their heads together on the same day. There is a lot they can do to diagnose and treat the problem as far as xrays, therapies and medication management. Did you see Akeela and Finn's story?