Regarding Danny's armies. I think when Danny comes out and tells everyone that the fight is not over, everything you see there, I think is her army. There are like a handful of Dokrathi, and probably a couple thousand Unsullied. The unsullied are supposed to be an elite army, so it's not a surprise that many of them would have survived. If you go back to an earlier season, not sure which one, but Jamie is talking to Cersei about the Unsullied, and he is afraid of them. So I would assume their survival rate would be pretty high.
So the next question is why didn't the other lords of the kingdom just kill the Unsullied and Dokrathi? Every kingdom, other than Dorne had basically lost their standing and trained army. In the previous episode, the soldiers with Jon look to only be peasants, not actual soldiers. So I do not think there would be enough manpower to take on the unsullied and win.