Rachael, welcome to 3FC!

on losing 33 lbs already, wow! Plateaus are tough, but they eventually end. You are doing the right thing by shaking things up and adding exercise.
The best exercise is anything you can stick with, so don't overlook sports that you may have always wanted to try, or starting with 5 mins of walking, anything you can stick to, and do it every day. One of the first things I did was to start doing 15 crunches each morning, before I even rolled out of bed...I just did them on my bed. It doesn't sound as impressive as a mega ab workout, does it? But, it was easy to do, and got my day started with exercise. It also helped strengthen my ab muscles, to help lift things up and in, so that didn't hurt, either! Think about what you like to do, or always wanted to do, and if it can be called exercise, start with that. Once the habit of daily exercise is in place, it's easier to add minutes, miles, or try new things.
You might like to check out the 20-somethings forum, to meet some people here, or just cruise the boards and jump in where ever you feel most comfortable!