My boyfriend and I (we are both 17) had protected sex on May 21th but the condom broke so I decided to take plan B. It happened late at night so I had to wait to get it the next day, I went to the store and I had to order plan B so I took it within 66 hours. I was in low chance of pregnancy in my cycle but I was supposed to get my period on May 25th and I didn't. Now I'm 7days late and I'm really worried but I've heard that plan B can change your cycle. Should I take a pregnancy test???