Hi, I've have developed calluses as everyone trying to learn guitar but my middle and ring finger ones have become kind of flat and are also very smooth. So when I try to do pull offs with those finger the string kind of slips and I cant seem to pinch them (at least thats what I think I am suppoused to do)

So I was wondering if anyone here have experienced something like this, if yu have any advice as how to overcome it (maybe I am doing the technique wrong) or if should do something directly to the calluses, I dont really feel like trimming them since it seems that it would be painful, but yeah, any advice on this would very much appreciated. Thanks!