
It sounds like she had a false start to her season (not uncommon) so she really is only just coming to the end of a proper 3 week season. I would keep her safely away from any male dogs (on lead road walking only) for another week, by which time the vulva should have lost that puffy open look, and be firm and closed.
I have often had the girls continue to hump each other even a few weeks after they finish, but there is no way they would let a male :D