You say you got her “recently” – how recent?
I don’t have a care suggestion – but believe she may just be a little “stressed” (depressed) due to the changes (“she is 7 and has been around the same horses her entire life including her dam”) and now she is alone.
Basically you just weaned her – away from “mom” for first time.
I personally like to groom on horses when they are feeding (untied in paddock).
They are standing still, can check for ticks, and is a great time for bonding. Perhaps this might help speed her up – not feeling “lonely” when she is eating .
Just a thought.