Why do my new eye gles make me seem taller?

It sounds like you just got your first (or much stronger) gles for nearsightedness. And what you describe is normal when there is a pretty big change in prescription. I had the same thing happen about a 1 1/2 years ago. I was leaving the shop with my new gles, went to step off a curb and almost did a face-plant in their parking lot. (Would not have been a very good "advertisement" for their gles!) Everything looked smaller, I was picking up 5/16" bolts thinking they were 1/4", 1/2" rod, thinking it was 3/8" a lot of swearing, etc. I would say it took about 2-3 weeks to get fully used to them. Be patient, you will get used to them.