Advice please

Hi everyone,

I have a 12yr old extremely introverted daughter who struggles socially. Following a particularly difficult event last night I found myself needing to look for advice and thought I'd start here. 

She was recently put on a ASD pathway.. nothing has happened so far but I do have questions. 

At what point does extreme introversion possibly become something more.. Maybe aspergers for example? 

Last night we were at my daughters dance schools annual awards ceremony .. She usually attaches herself to me and doesn't mix with other kids in these situations, she's never liked loud discos/parties like this so this is normal for her. But she's recently become close with a relatively new little girl and last night actually left my side to go & sit and talk with her friend(yey!).. However later on in the night you could see she'd hit a wall and just couldn't be social any longer to the point we're she ended up crying and on the verge of hyperventilating and she just needed to leave. Just before getting to this point you can see that she's unable to hide her struggle in front of her friend and it almost seems like she is being rude but I do try and explain it all as best I can before leaving.

There are lots of other little things that point me in the direction of aspergers but also there are traits she doesn't show so I'm left confused as to were to go. 

She shows interest in unual topics for her age (she's obsessed with musical theatre).. She mixes better with younger kids. But she doesn't seem to show the need to keep to strict regimes and can adapt well to change.

She has friends in school and seems fairly comfortable with them yet struggles to give a strong 'hello' or 'goodbye' to most other people.

I have noticed an issue with eye contact at times also.

She starts counselling next week - if she feels comfortable enough, because her voice never returned properly after a bad bout of laryngitis almost 2 years ago!! She whispers still and uses this as an excuse not to interact. Not quite as bad as selective mutism but similar. Her speech therapist talks about her needing resilience training and says it's anxiety but I'm not sure.

I haven't chased the ASD pathway yet as some of her traits seem so mild that even I tend to put it down to being an introvert as she's so happy at home. But socially somethings not right. She turns 13 next month and although everyone says she'll grow out of it, I feel its getting worse and/or less easy to hide and make excuses for it as she gets older.

We talk openly about her being an introvert and she will often say she's not a people person but she's also not able to function appropriately in social settings.. 

Does anyone have any advice or insight please? A book recommendation?

I'm not massively educated on ASD so please excuse any unintended ignorance on my part. At this point I'm a concerned mum looking for advice. 

Thank you. X