A.A.
This is normal many times. I have had many kids stutter around this age in my daycare--their vocabulary is really expanding at this point. They talk just fine now at age 4 or 5. I would take the doc's advice at this point and not interrupt her and encourage her to take her time, slow down, and get the words out. Be patient. If you notice other signs that he mentioned or it doesn't improve in six months I would consider a referral to a speech therapist just to have her evaluated. It won't hurt her, and if there is a real problem then you can intervene early. This most likely is very normal though, try and not worry too much. Best to you!