First things first. Make sure you can play your power chords with both your index and pinky, as well as with your index/ring. If the power chords are giving you trouble, the barre chords will be that much harder.

Secondly, using your pinky is fine but you are at a disadvantage with that. Using your ring finger allows you to be able to use your pinky and middle fingers as extra tools to play other notes. I would get in the habit of using your index and ring so when your ready for barre chords, you can add in your pinky to play an octave up AND your middle finger to play some other notes in the chord.

Best of luck! :D