safe to do abdominal exercises?

I'm 3 months pp now, had a c section. I still feel like my stomach is not put back together. I will try to contract my stomach (as if bracing for someone to punch me) and, its like, nothing happens. I feel so disconnected from my stomach, like my muscles arent healed up yet. I wouldnt dare doing any kind of crunches or sit ups right now. Is this normal? Should I be feeling my stomach again and be able to do crunches? Or at 3 months still have not have a normal stomach (i'm not talking fat wise i'm talking muscle wise).

I had one 2 mths ago and the doctor said if it hurts don't do it. I did my first PT today andI tried to do everything but I can't. Slowly work up a workout.