In high school I was same height I am now, didnt grow from 15 on. I was 185 soph year and colleges said I needed to be 220-230 to be recruited as a D-I fullback or linebacker. I went on a 6000 calorie a day plan where I wrote down everything I ate.
I would eat a huge breakfast, and in between classes at school drink an Exceed Sports Meal (think they are defunked now), lunch, another shake between classes, practice, a huge dinner, another shake few hours later with weight gainer, milk, ice cream, and before bed a can of tuna and 2 hard boiled eggs.
If I needed more calories for the day or on weekends or summer, I drank more of the milk shakes. You just need to make it a habit. I wish I was as disiplined now as I was then. But I went from 185 soph year to 235 senior year.
Of course those are growing years and the natural hormonal coacktail going on, but find some sort of MRP or shake you like drinking and drink it between meals. Or milk, banannas, peanut butter shakes, whatever your taste buds like. Make sure you hit heavy compound movements. You aint gonna grow if you aint squatting, deadlifting, and if you are lucky enough to have the instruction doing olympic lifts.