How to gain weight for 14 year old boy?

Hey, I'm 14 years old like I said and I'm about 160 lbs. It's not too light but I'm extremely lanky cuz I'm also 6 foot 2....I do work out everyday ya know upper body one day, then lower, then core, and I've actually gotten very strong. I've gained a bit of weight but nothing much that's visible. I drink tons of milk and eat bananas (that's what my mom said to do). Does anyone have tips to gain weight?