Her behaviour is telling you that she can't cope with whatever situation triggers it. She doesn't know how to express herself any differently.
The first paragraph of your first post and this should be enough for someone to see her reactions are different enough to warrant investigation.
it's more when she has a role play going on in her head (she has an amazing imagination) and her friends or me or the props don't do or don't want to do what she wants to happen
That would definitely be worth mentioning, rigid/inflexible thought patterns and unrealistic expectations causing overwhelm when things don't work out as she thought they would as she's lost control.
Girls often 'mask' meaning that as long as their academic progress is average and they don't cause major disruption at school, the staff say they are "fine" and aren't helpful when it comes to supporting a diagnosis.
Have a meeting with SENCO, but don't be surprised if they "see nothing" If they are actually on board, it's a bonus, but it's not impossible to have an assessment without their support.
Definitely ask for her to be assessed. Usually it's by a team of professionals Paed, Ed Psych, SLT and OT.
NHS waitlist is +/- 18 months to 2 years depending on the area you live in.
Ideally, a private assessment carried out by a team of professionals who also work part time for the NHS will be accepted by a Local Authority if you need to go down the route of applying for an EHCP. Some can put obstacles in the way if parents only have dx from solely private practitioners and request an NHS dx, thereby considerably delaying help for the child.
Ask on SNChat or SNChildren.
There are lots of myths about autism that even professionals perpetuate, so just ignore any references like she couldn't possibly be autistic because she can make eye contact, show empathy, we're all on the spectrum (no we most definitely are not) and anything else that doesn't form part of the diagnostic criteria. The misinformation about autism by people who should know better is staggering, as evidenced by Chrysanthemum5
For years I've been saying that she may have an autistic spectrum condition but because she can cope with eye contact, and is well behaved at school, I was told no and that she was anxious.
What you've been told is rubbish. Anxiety is part of autism in an autistic person, it's not a separate condition to their autism. Once you can find out what triggers the anxiety, you can start to provide interventions to pre-empt the behaviours that result from being overwhelmed.
There's a lot of info online about autistic presentation in girls, do investigate and if you think she has enough markers, ask for an assessment.
Another myth is if you pay for an assessment you'll automatically be given a diagnosis. It doesn't work like that. The assessments are recognised tests and your child will be scored and it depends on their scores as to whether they will receive a diagnosis or not.