Do you know anyone that is qualified to come just try loading her without your help? I am wondering if you are getting anxious and she is picking up on that so now she has developed this new habit?

Don't use any of the local yahoos, just maybe a family member or friend willing to just put her halter on and just load her up like she has never balked?

I freely admit this happened to me. I had a mare that was awful to load. When I got my present mare, that was my biggest worry, even though she had been hauled thousands of times. Very soon, I had another mare that would not load for me or even when I was in the vacinity. I was the issue. Not the horse, not the trailer. She was feeding off my aanxiety over wether she was going to load or not. So I had my daughter take over loading without me being present. Loaded like a charm. So everytime afterwards, I got closer and closer until I was loading her up myself. Now I know she loads, I don't give it a second thought, problem is resolved and she does, in fact, load just fine now.