Trouble with Bar Chords?

This questions I've seen dealing with this problem have to do with beginner guitarists, and so yes I'm a beginnner. I simply can't bar chord, I'm wondering if this is because I have such tiny hands, or is it truly a matter of just guitar practice? Because I have the buildup of skin on my fingers just not my bar chord finger, Is the only way to do better by keep practicing? Or is there a better technique to "bar" a fret? I can't reach around with my thumb [SMALL HANDS]. So I was wondering what else there was to try. Thanks. =)