Pitch Ages

Well, as you can see from below, I have four pitches to throw. Unfortunately, my curveball has to be on for me to hit the strike zone. As much as I practice it, I just can’t get it consistent regularly. This could be normal for pitchers, but when I say, I can’t find the strike zone, I mean I tell my catcher, NO curveballs. And then my change-up is fairly decent. It’s more-so a back-up for the curve.
I realize that fastball, curveball, change is pretty solid, but I was curious if there were any other “safe” pitches. I’m 15, 5’9", I think I still got at least 2 inches left to grow, weighin in about 155, and my fastball is in the low to mid 70’s. I was clocked a few months ago at 72, but it was a bushnell, so i dont know how reliable it was. And I think I’ve gotten my fastball up to 74, at least, since.

Alot of coaches would tell you to stick with your 3 main pitches and work with those before adding a 4th would be necessary.