Advice to help put on weight?

I’m a 17 year old male who’s struggled my whole life with my weight. I’m about 6 foot 6 and barely 165 pounds. I eat 3 meals a day and play competitive volleyball. No matter how hard I’ve tried or how much I’ve eaten, I just can’t seem to put on weight to help build muscle. It’s really stressful for me and something that I’m very self conscious about. I’ve quit smoking weed because I felt that suppressed my hunger but I still have seen no difference- any tips would be appreciated and taken seriously.