One thing vets look for is tartar on teeth. Up to a year old, maybe a little longer, there should be none at all. After a year there'll be small amounts accumulating near the gum. Eventually teeth can begin to discolor, but I dunno what age that would be.
All of this is moot if the dog had been fed raw. (My 12 year old's teeth have discolored but absolutely no tartar buildup. He's been fed raw since I adopted him at about 1 1/2 y.o. And he'd never had his teeth cleaned until a year ago when there was an intake mix up at the vet and he had a cleaning I hadn't ordered when he had a broken tooth extracted. Vet later told me she couldn't figure out why she was doing it because they were perfect.)
You say the vet estimated 2 y.o. when you got her, but don't say how long ago that was. If she's still developing pigment on her nose, she's still pretty young. Mine who had late pigment development got all they were going to get by about 2-2 1/2 years old IIRC.
The thickening nails also suggests to me that she was younger when you got her.
Males will very quickly but noticeably fill out right at about 3 years old. That was how I confirmed to my satisfaction Bodhi's approximate age. Rescuer and I both thought about a year and a half old, but 2 vets each estimated 2-4. When he filled out about a year and a half after I adopted him, I knew the rescuer and I were right. But that's not so helpful for your girl.
It's always going to be a best guess for rescues of unknown background, so most ppl will use an age range or other approximation, e.g. 4-5 years old (sometimes a 2 year span) or "she's around [insert age]."
Hopefully someone else will have more to add.