Can stimming be related to ADHD?

I noticed my daughter's strange behavior at around 18 months.  She flapped her arms and tensed up (almost looked like a seizure).  She did this when she was watching tv or playing with toys.  Her stimming has become more intense over the past 3 years but she has continued to develop socially and has hit all milestones.  We were sent to a neurologist at age 2 1/2 to rule out seizures.  Since then I have reported the behavior to out primary care who said that we should just keep an eye on her to look for missed milestones.  She has started kindergarten and the stimming is becoming a problem because now her peers are noticing it and they think that she is "weird".  I asked our primary care to refer us to a child behavior doctor to be evaluated for some type of developmental disorder.  I have a hard time describing her stim, but here it goes.  She tenses up, snaps or flaps her arms / hands, crosses or closes her eyes, her mouth is open and sometimes she makes a noise that sounds dolphin like.  She stims when she is playing with other children and also when she plays by herself.  She sometimes stims while interacting with adults.  She is very social, makes eye contact, no speech delays.  Is very smart.  Seems to understand personal space and body language just fine.  She does seem to be a bit on the hyper side.  She has a hard time paying attention but not all of the time.  Her stimming has become very obvious and happens quite frequently.  While playing in her playroom I would expect to see her stim at least 20 times in an hour.  She doesn't always stim however, for example if she were in a situation where she was meeting some one new, her anxiety may cause her not to stim.  She needs to be comfortable in her surroundings and be either playing or thinking about something (imaginary play).  Sometimes it is very difficult to get her to stop.  It is almost as if she needs to stim.  I keep calmly asking her to stop or replace the behavior with clapping hands etc.  but she will just go right back into her stim.  We have to wait 3 months to see the specialist and I am nervous that she will just be brushed off because she seems to be socially "fine".  Advice??  I can't seem to find anything about stimming without autism.  Very concerned and would like to be prepared for her consultation in 3 months.  Thank you!