Hi there. When I was in college, I worked in the main kitchen of my school as a prep cook. If your school is like my school, a lot of the recipes use mixes, pre-packaged and pre-made foods. Plus, the recipes that the school uses are to make quantities that will feed 500+ people. Have you ever used a recipe that makes 30 pans of lasagna? Or one that calls for 100 lbs. of grounds beef? I have.

I bet the cook or kitchen director would have a hard time telling you exactly what is in the meals... unfortunately, some things fall by the wayside when you are serving 1000 people three meals a day.
Try to stick to things that are pure, where you know all of the ingredients. The salad bar, fresh fruit, etc. Many schools also have a sandwich bar. Would they mind if you brought in your own bread? Steer clear of the soups too, unless it is a broth soup. The secret ingredient in the cream soups was "MORE BUTTER!!!" (A direct quote from one of my favorite cooks.) If your dormitory has microwaves available, you could try making your own frozen meals in your room, and stocking up on fresh veggies in the dining hall.
This will be difficult (trust me, I know!) but it is possible.
p.s. All of this reminiscing has made me miss my job in the kitchen... those cooks sure do make a fatty meal, but they are wonderful people. Maybe just not wonderful at Weight Watchers.