You're torqueing the string. Make a string bow and prove it to your self.
My opinion is you should be using a tab. Much cleaner release.
I go with this..You shouldn't try to create equal pressure across the three fingers. Your ring finger should only really have about 10% of the holding weight. I try to "bias" my string grip by starting to pull with middle finger only, then add pressure on index, and finally ring finger just to help stabilize the hand without applying pressure. Stopped my ring finger from hurting.