Hi Welcome to HM. Most of the time it is psychological. You have done investigation to rule out organic cause. Be relax throw all material from your mind Masturbation is normal physiological function of our body It is one the method to satisfy sexual pleasure in absent of partner both sex and masturbation has same and has same end result to get satisfaction. So excessive think can cause psychological stress.Constant thinking and feeling of guilt of masturbation will effect So no need to worry. Regarding premature ejaculation. Your anxiety and stress will affect your sexual functions Sex is mutual act. Premature ejaculation can be treated with both psychologically and drug therapy psychological means to learn how to stay long Certain methods like women on top position,condoms lubricated with benzocaine kegel s exercise will helpful .please read on net and learn how to do it Stop and start method of sex is very good results. it is thought diversion method and require time to learn . search on net to do it proper way read more on google Masturbating before sex can increase your time proper play and understanding is needed Condition can be treated with medicines like dapoxetine and mild dose of clomipramin if require. Thank you. Happy to help you.