10 year old daughter overweight

So my daughter is overweight and I don’t know how to help her. We eat a very healthy diet and I make sure she takes her vitamins everyday. We also walk about 2 miles a day and even the thought of walking or doing sports gives her anxiety. She stays with her dad/ grandmothers Tuesday nights and every other weekend (court ordered) so I don’t have much control over what she eats over there but have expressed my concerns about eating healthy.

Personally, I believe it’s a mental health issue she doesn’t have the best relationship with her dad he’s in and out makes promises and doesn’t keep them etc. Her relationship with food is terrible and is ALWAYS thinking bout her next meal. She looks at my sister and I and comments on how skinny we are

I have been doing positive affirmations with her and have tried therapy twice but it didn’t work out and our insurance doesn’t cover much.

She has a great mentor now we she has been working with for a couple of months but idk what to do. Any suggestions would be greatly appreciated