Help when diagnosed

My child is on the waiting list for an autism assessment. My child is currently receiving help from speech therapy to talk and on a waiting list for occupational therapy to help with eating. 

The traits showing within my child of autism are severe delay in speech but making progress, issues with food and textures of food within the mouth and will not sit down other than when my child wants to.

Does been diagnosed make a difference to my child's life if these are the issues and speech therapy, OT and a classroom assistant will all be helping?