Sorry for the delay.
Probably nothing will happen to you. They do not need very long to investigate this if they wanted to round you up and bring you in. As you registered for the site under an alias and with a false identity, they would have to find out who you were -- which would likely take technology the county police department does not have. From there once they identified you, it would only take a few hours to get a warrant and come in and impound your computer
, to see what all you're up to.
I just don't see them going to all that bother unless the comments got more sexually explicit or you exchanged explicit pictures or tried to induce her to have sex with you. Are you even sure she's under the age of consent?
In the unlikely event the state did manage to find and try to prosecute you, as long as she was NOT under 14, if you could have reasonably believed that she was over the age of consent, you would have a defense to this.
I'd relax about this one, but I'd be a lot more prudent going forward. You never know who an internet contact really is unless/until you meet her in person. Start getting to sexual and she could be an undercover officer or a blackmailer.
You should not have anything to worry about here.
Good luck to you.