If you're under 18 you are a child.
Having sex with a significantly older adult when you are under 18, like say any more than 2 or 3 years older might seem fine at the time, to your' developing young brain, but chances are that it will fuck you up. Even people in the age of 18/19 or early 20's can be manipulated/exploited much easier by older adults with more life experience, so even this pairing carries with it certain risks.
You say "under 14 years old children" I am assuming because you masturbate to 14 year olds and possibly younger children. It is important to note that sex between a 14-17 year old child and a much older adult is bound to have a very large power differential, and it is a recipe for trauma and possibly heartbreak for the child. It is likely the adult in this situation is interested primarily because "their partner" is a still developing child. Realizing this and getting discarded by your abuser, whom you may have even thought loved you, later on is one of the most damaging effects of childhood sexual abuse. Not to mention that people who sexually abuse children cannot in principle or in actuality obtain any degree of consent from the children they sexually exploit.
Sex between adults and children of any age is always exploitative.
Sex between adults and children of any age is always harmful.
Listen pedophiles, the truth is simple if you are honest with yourself.
You cannot choose whether you will develop a sexual attraction to children, perhaps you could say the same thing of necrophiliacs or those with an intense drive to rape, what you can choose is how you will deal with these drives.
Our mother nature is brutal and unfair, human beings and other social animals by contrast possess knowledge of morality and the ability to reproduce it.
Taking no actions to quench your desires may end up in you committing a sexual offense, it is your' task to deal with your pedophilic desires in a healthy way, it is society's task to provide you with the resources you may require to overcome the urge to abuse children. Should you fail in this task, it is society's task to hold you accountable for your actions, and for you, to accept your fate.