My 10y daughter is really struggling

My daughter (j) is nearly 11, is a perfect student, happy and loves school. At home she is very different. I really don't know how to explain it, she is just so different from her two sister who will entertain themselves with all sorts of things but J will rally take part. If she does, within minutes all free play imagination has gone and the rules to the game are made which irritate the other two who get bored after 10 minutes of being told what to do, how to do it and when to do it, with shouting and physical aggression taking place if they do not follow the 'rules'. Her anger is becoming worse, she will say the most hurtful things and can not see why people are upset, she just sees what she said as factual, she does 'hate' her sister at that moment. 

Even activities like coloring have to be organised with pens shared out and swapped at the set time. I merely mentioned one day that we should play more family games and within a day a spreadsheet had been drawn up with what days we can play, who is choosing on those days and what we could play. 

Dinner time is difficult as she is becoming more fussy with food, anything with a slight bit of heat is too spicy, food can not touch (not the end of the world if they do but a good few minutes are spent rearranging the plate) and she now is eating all of one item before moving on to the next.

J is very bright, top of her class for all subjects and enjoys maths that is several years ahead of her age, she cant get enough algebra! so we don't have any academic issues but we are worried about secondary school as she is becoming more and more anxious about being in groups of more than 3 or 4 (outside of close family), we have meltdowns with the thought of any large group activity. 

J is becoming isolated from her family and spending a lot of time on her own. she know something is different about her, we continually reassure her that everyone if different and we just have to find a way for her to cope with the pressures. 

We have been to the GP and had a referall to CAMHS but as soon as the school filled in the questionaire (she was marked as perfect with no concerns at all) nothing more was done, I have asked the school do make a referal to the local ASD outreach center but we are still waiting for any news of that. 

Is there any advice anyone can give as to how we move forward with trying to get some help.