Trimming can be a good thing, or the end of the call. I would experiment on one of your not-so-favorite, or older ones first. Trim all the way around in even increments to start, cutting 1/8" or less to start. You might only need one trim, might be more. Try to maintain the original shape, with a little more tape at the rear. You might do a "fade" trim going 1/8" on sides to 1/16" on the back, if you know what I mean.
Once you find a good fit, you can save that call and use it as a template for any newer calls. A better fit can make a big difference for fit & function, and sound. The goal is to find the fit that allows a good comfortable "feel" in the roof of your mouth. One that allows a proper seal, so the air is flowing across the reeds on just the underside of the call (cleaner sound), while still having enough tape to hold the call in place.
Not sure what brand(s) you use, but from my experience Hook's calls use a smaller tape to begin with. You might want to try one to see if you like the size. If you do, you can trim your other calls to match.
Experiment... a little at a time.
