Your not just accidentally going to get "BB big". It's going to take at least a year of consistent lifting and eating right to get "average muscle".
You need more calories to get bigger muscles, if your muscles aren't getting bigger you aren't eating enough. It's pretty simple, but not easy.
If you actually ever get to the point of "average muscle" that you want, just keep on doing what your doing and keep food intake the same...then you won't get any bigger. Food pretty much regulates body composition if your training is good.