I think you two look great together =] I think the universe is trying to tell you something as well, and I really don't think it would be a bad idea to keep her. From what you've said, I see so much potential in her and you, and I see you learning SO much from her. Sometimes it takes a horse who scares you and makes you nervous, to fix that anxiety. You just have to be confident in yourself as a rider, and she can feel that confidence the same way she feels your nervousness. I had some bad experiences with a naughty pony when I was still a crosspoles kid (I'm 22 now) that made me terrified of riding ponies. A couple years ago, my trainer had a 12.1 Welsh pony that she wouldn't let anyone ride because she was so bad: bucking, bolting, spooking, refusing jumps, etc, but she wanted me to work her because she thought I could handle her. I rode her on the flat about 4-5 days a week, and jumped her once in a week in lessons. I was TERRIFIED of jumping her for months, I would almost have panic attacks when it came time for us to jump our course. There were times that I did fall off, but it was always on the flat when she would spook at something. She did refuse jumps, but when we came at it again I'd growl at her and close my legs and get her over it. It got to the point where she would jump anything for me; jumps she normally spooked at, she didn't even take a second glance at. As the BO put it "You and Rascal have an understanding". And I got over my fear by subjecting myself to it, and making myself work through it because in the end everything worked out just fine.
I know it's hard for you right now, but if you can work through your fears of riding Amber you will be a much better rider. You'll learn things that you normally can't learn on a horse that is more push button easy. You'll be able to ride her one day like the man that did the lesson on her. I believe in the both of you =] And if you already have her now, why not try and make it work?