My 6 year old daughter eats so slow

Hi there 

So my daughter hasn't been medically diagnosed, but after I approached the school and drew their attention to what they were totally oblivious to, she was discussed at the County council SEAT meeting and based on my list of concerns, they were in agreeance that she is most likely high functioning autistic. I've done lots of research to see what I could do to help and have seen a marked improvement in her since starting her on a cocktail of vitamin D, Omega 3 and pro biotic supplements. The one area we seem not to be able to improve on however is her eating habits. When she was a very little and first venturing into eating family meals, she was a very fast eater. She barely chewed her food and it was gone! We had to try and slow this down after she was diagnosed with GURD following many months of her having vomiting episodes during the night, first thought to be CVS (Cyclic vomiting syndrome). Now she eats so slowly that it is the norm for her to take between an hour and 90 minutes to eat a meal and this is with constant reminders from me and her dad to eat, chew, stop daydreaming etc. I will confess that both of us are guilty of getting angry with her. With the best will in the world it's difficult not to get frustrated. We are very worried though that if we carry on this way she could form a negative association with food which doesn't bare thinking about. We just don't know what to do for the best. If left to her own devices, she could, I'm sure, sit at the table till bedtime with a cold meal in front of her, but because of the GURD we cannot allow this to happen. Does anyone have any experience with this, advice or tried and tested methods that could work.

Thanks

Kerri