I started ejaculating from the age of 15. I'm now 17. I can't stop it. Every day I do it. Is it safe or not? And the sperm, are they limited or there more?
Currently you are needing to ejaculate daily, which isn't unusual for a young man. It will slow back down as you get older.
Ejaculating is not harmful. It is what your body is designed to do. Where problems can arise is the temptation to use sin to cause you to want to ejaculate. You are not to look at pornography or use lustful thoughts to cause to stir up yourself (See I Thessalonians 4:3-5).
You will not use up your sperm. Once you start producing semen, you produce sperm until the day you day. There is no limit on the quantity you produce. The only limit is on how fast you produce semen. Your testicles, which are below your penis and in your scrotum, produce about 100,000 sperm cells every day.