I'm 17 years old, and I am kinda worried about the volume that I ejaculate. When I masturbate, very little comes out, and I'm wondering if anything is wrong and if I'll be able to have kids in the long run.

The typical load of ejaculate should be about 1mL of fluid (about a teaspoon, for you metrically-disinclined folks). That can vary depending on how often you ejaculate. If you ejaculate three or four times a day, expect the volume to be less than if you were only ejaculating once per week. Semen volume depends on how productive your prostate and other associated glands are. The bulk of semen volume is made in the prostate.

Your fertility depends on the quantity and quality of sperm you produce. You won't need to know that right away, but someday if you and your partner try to conceive, your doctor can test your sperm count and check your sperm for defects. If anything's abnormal, your doctor can discuss your options with you at that time. Chances are, if you do have an infertility problem, your doctor will either refer you to a doctor specializing in assisted reproductive technology, or you'll be referred to a urologist (a doctor who specializes in the urinary bladder, urethra, penis, prostate, etc.)

But for now, I doubt your ejaculatory volume will have a significant role in your future fertility. Don't be dismayed because male porn start seem to put out a lot of fluid. Porn has a way of skewing our view of how our bodies should look and function.