You have mixed up issues here. Not being circumcised you cant masturbate, who says so? It doesnot happen.
Having perfect ejaculation and not ejaculate good amount, that has different logic. I can explain that, but you havenot masturbated still ejaculates, how you will explain that?
Again mising up ejaculation with fertility, thats another mixup. Summing all together, you have asked a complete confusing question.
When you ejaculate, main part comes out is semen, alog with sperm. Sperm is responsible for fertility, not semen. Whether you are fertile or not doesnot depend on semen or quantity, its on sperm count on you. out of few million healthy sperms only one is required for fertility. Quantity is not a big issue here. Sperm is microorgan, you cant see in open eyes. So what you release and how many sperm are there you never know.
If you have problem with foreskin to stuck on the corona and not able to go through a proper masturbation, check with a doctor. I explained on phimosis before, you may need to go through an ointment or a small operation.
Nothing serious my friend, a doctor can explain you better than us.