I am 5'9", and have a very hard time building muscle. People consider me to be skinny, because I weigh 130-135 pounds. I would not be considered "cut", but you can tell my arms and legs are a teeny bit more muscular than they were before I did strength work. My stomach holds on to the fat, though, and sticks out more than I like. I have found that I get "fatter" when I eat until I'm full, and can lose 2-3 pounds over a couple of weeks if I spread the food out over each day. I count calories, and the calories DO count, but it seems that the same number of calories don't keep the weight on if I eat smaller meals/snacks and don't pig out once or twice a day. I try to stick to 1900-2200 calories a day, except for weekends, where I will drink some beer/wine and forget about the calorie counting.
Since you know how many calories you need to eat, try spreading them out over the day and see if it helps even more!
Sandi M