Well, your RC's are good and all, but you have to be in a state of critical awareness. You have to really believe you could be in a dream, and ask yourself questions, like "Is this real," or "Am I dreaming," or even try to remember what you did a couple of minutes ago. Then that's when you perform the reality check, while repeating your mantra. And only 5 reality checks may be a bit lacking, I'd give it around 7-8, or 10 if you can.

But this will take some time, so give it at least a month of consistently doing it to find good results. You know you're on the right track when you are close to starting to do a reality check without thinking about doing one, meaning you don't think, "it's time to do an RC" before performing one.

Best of luck! Sweet dreams..