I'm not US based but in the UK if, as you appear have to have done, you held your hands up and admitted your guilt that should be that. In all likelyhood the CAA would "give you guidance" and, providing that it's your first misdameanour, your Chief Pilot (or the Senior Based Pilot) probably would have a word in your ear, possibly roster you with a check Captain for a few flights.
Runway incursions are a very serious issue and the UK CAA and associated organisations encourage ATC to report such incidents so that we can all learn from our errors rather than point fingers.
Hopefully the FAA would take the same stance.