I know that it is very hard not to take this personally since you feel that others are doing the same thing and not being called to account for it. But what is your facility's current policy? That is the process you should have used. Medication reconciliation is a huge pain in the neck for everyone.... but it has been proven to be a big safety risk also & a major source of med errors.
As a charge nurse, one of your major responsibilities is making sure that everyone adheres to the approved policies and procedures. I know that this sucks big time, particularly if you feel that there is a 'better way' or that the P&P are outdated. If so, you need to work to fix the P&P. If you violated policy, your boss may not have had a choice in determining your 'punishment' but I would encourage you to discuss this specific issue with her in order to seek clarification. You're right - if that behavior is 'wrong', it is wrong for everyone, not just you.
This may also be a good opportunity to address the policy - via inservice or staff meeting - to make sure that everyone is on the same page. At the very least, take the time to meet with your 'team' and make sure that they are on board.