First of all remove all myths & misconceptions from your mind about masturbation
In fact, Masturbation is completely normal & doesn't have any bad effect to the body and mind.
Also night emissions are a common thing at your age.
Regarding the problem of premature ejaculation
, it's mostly related to anxiety.
So...don't worry about all this & stay relaxed
Avoid stress...practice meditation..this helps in improving concentration & builds up the confidence level.
Have a diet rich in fruits, vegetables, fish, nuts & honey.
Avoid smoking & alcohol.
Despite these measures, if you experience difficulty, it will be better to consult an Urologist
to rule out other causes like high blood pressure
, blood sugar and other local causes that impair blood flow to your genital organ.
One more thing...avoid consuming any over the counter medication
which claim to increase the size of penis or improve performance...it may be harmful.
Wishing you a Healthy Life.