Every video I watched, here and YouTube, states the end of the thumb is supposed to be used as additional support on the back of the fret board. However, this is too painful for me and my chords sound aweful. The only way, so far, I can play is using the mid-section of my thumb.

I'm using a Fender Squire Stratocaster. My hands measure as the following:

Hand (from palm to tip of middle finger: 6"

Thumb: 2 1/2"

Index Finger: 3"

Middle Finger: 3 1/4"

Ring Finger: 3"

Pinky Finger: 2 1/4"

I've been curious if my hands, part or in full, are too small or if improvising like I'm doing is acceptable. I know everyone has their own playing style but I don't want to learn bad habits or injure my wrist.

Thanks for reading!