How fast can you throw a baseball. No exaggerations!?

Im 20 and last year when I pitched in college, my avg speed on my fastball was 87-89. Have hit 91 but that was when I just when I was at practice and was trying to throw the hardest not worrying about where the ball was going to go. Like my pitching coach told me, a pitcher can throw 100 mph, but if they cant continue to throw it for strikes they will never pitch.