I need your help please urgent

I had protected sex with my boyfriend this morning and the condom broke. He didn't realize it broke until we were going into a 4th sex position. He never came in me and he didn't really have any precum.  Now, I'm supposed to be getting my period any day now and when I wiped myself after having sex with him I saw some spotting and I've been lighting spotting since.  I want to know if I could get pregnant? If I should take plan B? I don't know what to do please help,