I know the feeling. I remember when I first started and every time I flew it seemed like the plane was screaming too fast to keep up with. Now after two years of flying fast can be super fun! There is not a single reason I can think of for an instructor to make a student fly the plane at full speed. This is not good at all. It is much better to learn incrementally with plane speeds as confidence builds. The first time we ride a bike, we don't go as fast as the thing can go and start doing flips and stuff. With the information you have given, I question the instructor in this case.

Instructors sometimes forget how they started out, the fear that can accompany a learner, and since they have been flying for years just go into some sort of auto super confidence fly mode and that is not good for some students. I wasn't nervous about flying when I started out as much as I was nervous about crashing my "only" plane at the time and would not be able to fly until I had another plane. I hope you can get some good help so you can really enjoy flying. It is so much fun when learned properly and brings many hours of rewarding pleasure.