Does she understand the concept of imaginative play? I would give that some consideration. My DD (now 10) understood the concept but was not interested. When I tried to play with her, she'd just laugh at me like I was some sort of idiot. She was ultimately diagnosed with ADHD--not sure if that had something to do with it. Other than that, she never had any indication of delays or a disorder like autism. She has played with dolls on and off but not in much of a role playing way. Mostly what she has done is rip their heads off.
If you have concerns I think it would be good to start with a developmental pediatrician or neuropsychologist. If you want services like speech through the school district they will need to do an eval, but if you can afford it it's a good idea to get a private eval first and take the results back to the school. (we have had school evals that were very poor to put it mildly, and then those results are stuck in the records and a lot of schools are biased and do not want to provide services unless they have to--I can't tell you how many times we've had the people with the schools say "everything's great" when that obviously wasn't the case.)
Edited to add, I wanted to point out the twice exceptional forum on this site--lots of good info.
