It's not the booster...if that fails you will have hard pedal, but you will have brakes.
If you had some brakes, probably rear, the mc is very likely the culprit. No pulling right??? Does it pump up?
The other possibility is that you have a leak, either front or rear, and you are using only one end of brakes on the car.
Just remember in an emergency, there is always the emergency brake (manual). Also used to practice bootleg turns...
