Have you looked into Stroller Strides? Stroller Strides - Prenatal exercises for mom, postnatal exercises for mom
A friend of mine joined (until her babe was no longer in a stroller) and she loved it. Loved the company, the workouts were really challenging, and it was fun to do stuff with here daughter.
Obviously, I don't know whether there is a group in your area, but they tend to form kind-of spontaneously.
Good luck getting back to the old bod!