Hi,
Welcome to HCM,
Firstly remove false fear of having any bad effect of
masturbation in your body or health.
It has no bad effect on production of semen.
Yes due to frequent and short time duration of masturbation does effect quantity of semen as formation of semen takes some time, so at this time quantity might be less.
Keep in mind that every thing in excess always to be avoided.
Ok and bye.