How do I lose weight?

Growing up I was always very slim. I tried everything to put on weight. And now it's the opposite. I used to eat more back then and have always done little to no exercise..i know that's bad.. but when I was skinny I didn't want to do anything that would make me lose any more weight. I used to get bullied because of it. And now, I am overweight and idk how. I barely eat, and my portions are small, at least the same size as my 9yr old brother. My eating habits have always been the same. I have breakfast and then I don't eat till around 6-7pm. I don't snack throughout the day. But weight seems to just pile on. Help?