Welcome back!
I could be wrong but I think a big problem for a lot of people is that they aren't really aware of what they are eating when they don't think about it. For example, my Mom thinks those little packets of ramen you can buy are one serving. They are actually two. So what you are getting is ~380 calories in just one and that's not much food, nor is it good food. My brother eats two...that's a lot of calories and sodium for one meal! So maybe it's not that you were eating a lot but just weren't really aware of what you were eating?
Oh well, you live and learn! You'll get back on track in no time!