College freshman needs to get and STAY on track

For the first few months of college, I didn't gain weight and even lost a pound or so because I was absolutely petrified of gaining the "freshman 15". 7 months and 12 pounds later, I needed to lose the weight that I had gained before summer. I lost 4 pounds in a few weeks but gained 2 pounds back over spring break and have only "maintained" the high weight since. I really need to lose 8 pounds in the next four weeks. I am fairly good at sticking to a routine when I am busy with schoolwork, etc. (busy, but not overwhelmed), but I often consume far too much (and foods that are NOT healthy) in social situations because food (and alcohol--which is high in calories) is a huge part of the social life here. How can I get on track, stay on track, and avoid temptation even in social situations? MFP has helped me lose 5 pounds twice, but I gained it back both times (my own fault). Thank you so much for your help....getting on track for a healthy lifestyle and a healthy summer is very important to me!