1 week late period after taking emergency pill

Hi all, i'm a very scared boyfriend (i'm 25). This is about my girlfriend (she's 24)  who should have been having her periods by now but still hasn't. Her period started on 17th of june, we had sex on 19th/20th of june. Within 24 hours she had the emergency pill. I usually dont ejaculate inside her, we usually use the pull out method. I know its not 100% safe but trust me, i'm a guy. I dont lie when i say i dont usually *** inside her. I know we were in the 'safe' period, on top of that she had the pill. But for some reason her period still hasnt started. Its 24th july now. She had a test couple of days back but it came negative. Nor has she the signs like sore breasts, nausea etc etc. Please advice me anyone, as i'm freaking out here. Thankyou.

[mature_enough]

I know you can't help the way you feel. Fear is a normal emotion when you suspect you might be taking on a big responsibility.

What may be happening is that her hormones can be "messed up" from the pill. Read the side effects.

Otherwise, you may hear this 100X's, but only because it is true. If you don't want a baby, the most effective way is through protection. Birth control and condoms are a safe alternative until you're ready to take responsibility for life you may bring into this world.

Best of luck to you and your girlfriend.