Sperm count = the number of sperm cells in a given volume of ejaculate. The sperm have to be seen with a microscope.
Semen volume = the volume of the ejaculate, the amount of jizz that comes out with ejaculation.
Orgasm = the pleasant (mostly) sensations that accompany ejaculation.
Ejaculation = the expulsion of semen (sperm cells and other fluids) by rhythmic contractions of the muscles during orgasm.
You’re getting your definitions mixed up. You could only know you have a low sperm count if you had your semen analyzed at a laboratory. What you’re talking about is semen volume.
Obviously, the more times you ejaculate, the lower the volume because the body has to make it each time you cum. If you jerk off seven times in one day (why do you do that?) then your body won’t be able to keep up with production.
See: Ejaculation Process