How long does it normally take for everything to go back to normal after a season? Sasha finished her first season about 3 weeks ago, bleeding all the way through. Her vulva and nipples are back to normal, but the area around each nipple is a bit swollen and firm. Is this normal? She's not pregnant as no males dogs have been to her.

Can anyone help? :(

It depends entirely on the bitch. It could be she is 'back to normal' already! She will never have a 'puppy' figure again - and she will undoubtedly have a degree of false pregnancy in a few weeks time. To minimise the chances of this give her raspberry leaf tablets, don't feed her too much protein, and keep her active.
:)

She is still developing physically after a first season, if she has a phantom preganancy it could be three months or so before she regains what will become her normal figure  (two months for the pregnancy and one (or two) months for the swelling and milk to go down.