Had protected sex, still no periods.

My advice is to see a doctor about that... could be many different reasons why you are not getting your period and some of those reason can be hazarous to your health.. see a doctor honey.

Condoms do fail. They have a pretty high failure rate. If you use condoms it is best to also use some kind of spermicidal insert as backup just in case. If he entered you at any point without a condom even if he did NOT ejaculate in you, you could be pregnant. Nerves, illness, fatigue, stress.. these can all play into your period not showing up on time. If you are late for your period at this point, you can take a pregnancy test and then you will know if that is the issue. If it's negative, consider calling your doctor and asking what they think. Cycles do skip on occasion but it's best to let them know so they can decide the best course of action. Good luck and best wishes.