Dear Ms. Communicate,
Dear The Office Nag,
My next suggestion might be harder for you to do: STOP! Stop reminding, stop leaving notes and stop doing tasks that aren't yours to do. This might be challenging for you, since it seems to me that you and the co-workers may have developed a dynamic where they don't do tasks, you "nag," then you do it. See the pattern? They know you'll do it eventually, they clearly have a higher tolerance for the tasks not getting done (or they don't notice, or they don't care), and it clearly is making you unhappy.
However, if the tasks you refer to are part of their jobs, this could be a larger concern than you just being a "nag." This situation may have to be brought to the attention of a manager or supervisor. This might seem drastic, or sound like I'm suggesting you rat them out, but if they're goofing off, it's not fair to you and your workload. Nor is it particularly productive for you to continue with the status quo since it's bugging you so much. Going a level deeper, maybe there's something about your personality that tends to have you enjoy being "the reliable one" who always picks up the slack. In my experience, the kind of dynamic you described is rarely one-sided. Good luck!