If you entered on 5th October then your 90 day report is due by 2nd January, not 5th. The window to do it online is open now. Coming back from abroad does not prevent you doing it online, although it's been said that a first ever report must be done in person.
If I were you I would submit it online now using your Bangkok address and cross your fingers it gets approved. If not, change your address and do it locally in person. You have until a week after the report date to do it in person which is handy as any post New Year holiday rush can hopefully be avoided.