You are correct: Plan B may lead to a later-than-usual period. If the last time you experienced bleeding for a week began on May 16th, you probably need to wait another week (even two) for your next period.
You can take a home pregnancy test if you are not able to just wait for a period, if you need to know if you are pregnant or not. A HPT would be about 99% accurate at this point in your cycle.
Plan B is not 100% guaranteed to prevent pregnancy, no matter when you take it. It reduces your risk of pregnancy by about 80%. The likelihood of you ovulating on Day 7 of your cycle is not high, but it is not impossible, either.
This statistic may help you: women have "only" a 20% chance of pregnancy with each cycle, so there is more of a likelihood of you not being pregnant if this has been the first instance of birth control failure (the more instances, the higher the chance...just statistics).
Please know that condom failure is usually due to user error, and there are ways to help prevent this from occurring again in the future. For more information, please review this article: Help! The Condom Broke During Sex: How to Prevent "Wardrobe Malfunctions".