Age in my opinion does not matter. However, as Rich99 said, are you actually sexually active? Are you always into having sex, have you got the feeling of doing it..etc... if you know what i mean.
The are only 2 ways (that i know of and the main 2 ways) where you can increase ejaculation/produce more semen:
1. Drinking plenty of water
2. Being sexually active
im 20 and i have sex probably 2 times a week, sometimes less, and only masturbate occasionally
First of all, what is your age? Second, how frequently are you sexually active?