Popcorn or just an apple with pb is a terrible idea for dinner. Lean protein and some veggies are a much healthier option than starchy popcorn. You don't need to eat a lot of it, but protein keeps you fuller longer so you won't get the munchies before bed. I could never exist on just popcorn or an apple for dinnerBreakfast is the most important meal of the day, Lemon. Have a good one. Don't just eat cold sugary cereal or a sweet pastry. Have some protein. Egg is good. Have something whole-grain. Oatmeal is awesome, with fresh or dried fruit. Take your time, enjoy it. Get up early if necessary. It gets your metabolism going!
Lunch is the second most important meal. Have some vegetables. You may not be hungry at noon if you had a good breakfast. Eat when you're hungry. Salad is a good choice. Cottage cheese or yogurt are good sources of protein, again with fruit.
Have a light dinner. Maybe an apple with peanut butter, or popcorn. The less you eat the better you'll sleep brcause your stomach won't be trying to digest a heavy meal. And you'll wake up hungry for another good breakfast! Drink water between meals rather than with them. You'll digest better.