You can send an email with the file (false positive or infected) to: virus@avast.com You can zip and password the files… Inform a link to this thread and the password used.
You can send the files to Chest and, from there, resend to Alwil for analysis.
You can use Alwil FTP server as a second way to transfer only big files. Upload them to ftp://ftp.avast.com/incoming (please, note that you won’t have READ access to the ftp server, just write - so you won’t even be able to see what you’ve just uploaded).
Generally avast won’t contact you unless they require any more information.
If Virus Total and Jotti are showing only avast detecting this then I think you have little to fear, considering you have been using/had this program for over a year.
Did you put False Positive in the emails Subject as this may separate it from the other 3999 emails that avast receive at virus @ avast.com per day. You would need to do that after the email is in your outbox as I don’t think you can change it from the chest process of compiling the email info.