It is very normal for mammary glands to be enlarged/nipples enlarged during and after their heat cycle. In fact, after a couple months, the mammary glands can acutally fill up with milk if she has a false pregnancy. This is not uncommon, and is acutally a natural phenomenon in dogs. It usually resolves on its own with time. (If not, you can ask your vet for help).
It also takes several weeks for the swelling in the vulva to completely go away.
There doesn't seem to be anything to be concerned with here.Images available only to Customers.