There's a fun way to test out how much finger pressure you really need. Keep your thumb off of the back of the fretboard. See if you can fret notes and chords without having your thumb touch the guitar at all. Sounds impossible, but its actually quite doable, and once you try it a few times you may find that you can ease up on the amount of finger pressure when you go back to placing your thumb behind, or wrapped around, the fretboard.