Hello,
Thanks for choosing health care magic for posting your query.
I have gone through your question in detail and I can understand what you are going through.
Masturbation is a safe way of expressing ones own sexual desires. It leads to no physical or mental problems. The sperms and semen which are formed in the body are meant to come out of the body. They cannot be accumulated in the body and like urine they are formed in the body and are thrown out. They may come out on having sex or during masturbation. If you are indulging in none of these then the sperms and semen will come out at night by self (night fall) or routinely during any sexual stimulation. This is a normal phenomenon and will not cause any harm to you. Masturbation is safe and will cause no harm. It is harmful only when indulged in excessively leading to avoidance of normal work and schedule.
Your short period of comming on masturbation cannot be compared to the actual sexual experience. Its very possible that the sexual time during actual sex could still be normal. However if the problem persist even during actual sex then the same can be dealt easily. but not to worry as of now.

Hope I am able to answer your concerns.
If you have any further query, I would be glad to help you.
In future if you wish to contact me directly, you can use the below mentioned link:
bit.ly/dr-srikanth-reddy
                                        
Wish you good health,
Kind regards
Dr. Srikanth Reddy M.D.