Your paper seems to be progressing quite smoothly and quickly. Many journals take months to complete peer review. You are lucky that the peer review of your paper was done in three weeks despite the holiday season. Once the editor has evaluated your manuscript, it could take a few weeks for the final decision. There is no reason to think that your paper will be rejected considering the fact that the editor and reviewers have been quite expeditious. Even if the decision in process status takes a couple of weeks more, you have nothing to worry about. Sometimes, the editor needs to take the help of the editorial board to come to a decision if he or she is unsure about a paper. If this is the case, the decision could be delayed by another couple of weeks. If the status remains the same till the end of January, you can write to the editor. Till then, you have to be patient and keep up your hopes. Good luck!