Lost 20 pounds but now I'm nervous about eating?

So I'm 5'8 and I've lost around 20 pounds since May (went from 158 to 135) just by not overreacting and exercising. But now that I'm at a pretty good weight, I'm always nevous about what I eat and whether or not it's gonna make me gain weight back. I know that sounds really stupid but everytime I feel like I'm eating too much of saying something that isn't that healthy, I always get scared that I'm on my way to becoming the weight I used to be. I still work out too, just not as rigorously/frequently as I used to because it's hard between school and work. How do you guys manage your weight/keep it where you want it to be, while still eating what you want on occasion?