Hi Christina,
Building muscle with power excercises will be more productive when it comes to moving large loads, hiking with big pack, etc.
Size is all relative... Your small muscles require less h20, calories, effort, to maintain... Allowing you to carry less.
Just work on increasing power to weight ratios and dont worry too much about being small.
Good general excercises for building big power:
SQUATS
deadlifts
lunges

You will be motoring around with a 5 gal bucket full of waterin each hand in no time... <img src="/images/graemlins/wink.gif" alt="" />