No way can masturbating cause gyn.
They are both related, however, to your hormone levels. You probably started masturbating around puberty, when your testosterone production increased, and for many adolescents boys, some of that extra testosterone can get converted into estrogen through a process called aromatization. The extra estorgen is likely what is causing your gyn. This is why body builders can't just inject massive amounts of testoterone. The body will just convert it to estrogen. That's were "bitch t i ts" come from. Even if masturbation could cause it, you wouldn't see a difference in a matter of days. Change would take months to notice. I'm no doctor, but I've done a fare amount of reading, and your type of gynecomastia is pretty common among adolescents. Most of the time it goes away on it's own, within a few years.
Another thing to keep in mind is that regular ejaculations seem to actually be good for your prostate gland. You're a long way away from having to worry about prostate problems, but studies have shown that men who regularly ejaculated throughout their life, either through masturbation or sex, were less likely to have prostate cancer.
so jack off, banana, it's good for you.
The one reason I can think of, to masterbate less, would be to get so horny that you're more driven to try to meet girls. I used to try this when I was your age, but I don't know if it ever really worked. I could never hold out for more than a few days.
P.S. it won't make you blind, or give you hairy palms either.