Hey Ed I have split this post in hopes of you getting some more responses.
My first ds was quite small for his age so we always made sure to feed him high fat choices. Full fat cheese, yogurt, milk. Avacado is also high calorie and good for them. The trick is to stop feeding her chocolates and sweets and only offer healthy choices. Be prepared cause at first she may lose weight an refuse the food because she is used to you giving her sweets when she refuses other food. Trust me when I tell you she will not starve herself.
{{{{HUGS}}}}