You're obviously going to need at least one more port pin:

An n-bit binary code has 2^n (2 to the power of n) different combinations; thus, a single bit gives you 2^1 = 2 different combinations.
So you can use a single pin to control either the on/off for the motor, or the forward/reverse, but not both!

With two bits, you get 2^2 = 4 combinations.
You could use one bit for on/off and the other for forward/reverse:

bit1 bit2
 0    0   Motor=Stop; Direction=Forward
 0    1   Motor=Stop; Direction=Reverse
 1    0   Motor=Run;  Direction=Forward
 1    1   Motor=Run;  Direction=Reverse

Obviously, this gives you a redundant state, as the Direction is irrelevant when the motor is stopped!
You could, eg, decode this for a "Brakes On" state?

However, as already noted, if you really have a stepper motor it's a lot more complicated than this: you have to actually control each step, rather than just "Go" or "Stop"
Or maybe you have a stepper motor plus some sort of controller?