Dear Welcome to HCM We understand your concerns I went through your details. Masturbation has no direct side effects. Masturbation is healthy, natural and is a normal adult procedure. Almost everyone across the globe masturbate and get sexual pleasure. But in your case, at your age, masturbation twice a day is not advisable. You can do it thrice a week safely. Otherwise, your wrong knowledge about the negatives of masturbation can make you anxious and health obsessive. May be because of this health anxiety, you are experiencing the premature ejaculation. Don;t worry. You will be able to do well sexually after marriage. If you require more of my help in this aspect, please use this URL. http://goo.gl/aYW2pR. Make sure that you include every minute details possible. Hope this answers your query. Available for further clarifications. Good luck. Take care.