There's a few things that could be going on, but first, let me state that I'm not a health expert by any means. You are 15, so there is a good chance that part of your weight gain is contributed by the fact that your body is in it's peak growing time. Your bones are growing, your muscles are growing, so naturally your weight will increase. Now, seeing that your diet consists of a small breakfast and dinner would concern me, because you may not actually be giving enough of what it needs. A common myth in thinking about weight, is that if you eat less, you'll weigh less, but at your age, your body needs energy, and not feeding it isn't going to help it. Most importantly, and this may be hard to understand, don't get too wrapped up around your weight number. Peoples bodies are different, and one person's density can be different from another. My suggestion, would be to actually increase your diet to having a small, but nutritious lunch. Your body is an engine, you should be feeding it 5-6 times a day, just in small portions. The less food you give it, the less it will run, thus making bad weight stick around. I hope this helps a bit
