I'm sure you are feeling the pinch. :(
For a lot of target practice you may want to go to a longer bow and then resume the shorter bow later. Personally, I draw 32" and even with a 70" bow, I still get pinched after shooting a lot. My main hunting bow is 64".
Some will say that you should not get any calluses, but I have not found that to be the case. Can't tell you for sure that it is not your shooting. Personally, I shoot about 400 arrows per week and I do have to do maintenance on my calluses. I use a file, fine emery cloth, and good moisture cream suggested by my dermatologist every other day. If you continue to do what you are doing the callus will only get worse without maintenance. You really do not want it to get out of control or get a blister under it.