When I ejaculated, fully white slimy fluid came out -- about 3 large drops. I am 14 and stage 3.2 in the Tanner stage quiz. Is this normal for my age and Tanner stage? How developed am I in growth because of this?
The white fluid is semen. That is what normally comes out when a man ejaculates, though usually in greater quantities (about 1 to 2 teaspoons typically are ejaculated). Semen contains your sperm that will one day get your wife pregnant.
I suspect that before you've been reaching orgasm while masturbating, but all that was coming out was pre-ejaculate fluid (a thinner clear fluid).
Being able to produce semen is very normal for a teenage boy. It is another step toward becoming a man.
I can't second guess the results you received from the Tanner Stage Caculator. I can't see you to double check your answers, nor do I even know what your answers were. Being at stage 3 means you are entering the phase when you will rapidly grow.