You sound just like me! I'm kinda in the same boat you are. I have been with a couple different trainers and I feel sooo guilty when I have to go somewhere else. My problem is that I become friends with my trainer. One thing you have to remember is think more about yourself. Don't be such a people pleaser. Your old trainer doesn't have to know that switching to someone else. Just let them know you won't be taking lessons as frequently. In reality they probably went thru the same thing and probably won't be as offended as you think.
If you think about it all the trainers I know have studied under many other trainers. You take in a little bit from each one and transform it into something that works for you. You are eventually going to get to the point where your current trainer won't have anything to offer you. You will learn everything she has to offer.
I am never satisfied with a trainer. There was one trainer that I just loved and was everything I was looking for then she up and moved on me. I have no idea where she went. I can't seem to find anyone else that lives up to my expectations. Right now I found a good instructor that is able to explain things well to me but she shows Arabs and I show Paints/QH. Some things are very different in those worlds. So I try to take a lesson with a stock horse trainer at least once a month just to make sure I'm keeping up with the "fads".
So my advice is to take as many lessons as you can afford, and take the most lessons from the person that will be able to help you most. You are paying for a service and well you should be getting what you want not settling because you don't want to hurt someones feelings.