Can't lose the freshman 15

I am 5'8" and about 140 pounds. I am currently a college sophomore and unfortunately gained the freshman 15, for the past 10 months I have been trying to get back down to my size before I started college. I was 125 pounds and a size 2, now I am around a size 4 or a 6. I tried everything and even did insanity for 9 weeks and still can't get down to my old size! School has started up again and I have been eating healthy for two months now and haven't lost a single pound. I track EVERYTHING I eat into the MFP app and only drink water. I use the Nike Training Club app for workouts and do them 3-5 times a week. I eat around 1200-1600 calories a day, it depends on how active I was that day, I try to eat as clean as I can in my dorm room and stay away from the cafeteria. Most days I have oatmeal and a luna protein bar for breakfast, a plain turkey and cheese sandwich for lunch, for a snack I either have a luna bar, fruit, or almonds, and for dinner I normally make a rice cake and peanut butter sandwich. I try to track my progress based off of photos and how my clothing fits since ultimately fat loss and inches lost is more important than pounds. I look the exact same and still can't fit into my clothes. What is wrong with me that I can't lose inches or weight with healthy eating and working out? Please help, I am so frustrated and feel like my hard work and dedication has gotten me no where.