I seem to always be the debbie downer on these threads.
My only concern is that you mentioned you don't want to show and you want to ride at home?
Be aware that if you decide to sell her in a few years you would decrease her value by not getting her experience off the farm.
Also, I don't think that being ridden by a 12yo means much. If she's ridden by a trainer 4 days a week then being ridden by anyone once in a while isn't going to change her behavior. I would look closely at how often the trainer rides her, many times a talented but looky horse with a trainer turns into an uncontrollable monster with only an ammy. If she still stops and looks at things with a pro riding her consistently how bad is she going to be if you take the pro ride away?