Yes you can exercise again and it's perfectly fine to have physique-related goals, but you absolutely must remember that you just grew, and birthed a human being.
You're body is never going to be the same and that's a beautiful things.
I know it's easy to feel bad about weight-gain, scarring, stretching, and the many changes that our bodies undergo, but the more you focus on trying to make your body what it used to be, the more disappointed and frustrated you will feel.
Blaze a new trail.
You are new and different, strong and awesome.
Take care of your new and different body.