Teen mama??

So yesterday my boyfriend and I were having sex and I'm not a 100% sure what happened but apparently it started leaking or something and he noticed it but just kept on going. Not telling me. He told me a while afterwards after the damage could be done. We're both 14 and both him and my aunt want me to get plan b. But idk how comfortable I am using that stuff and even if I wanted to I can't because the rest of my family is Mormon I'm just inactive and so that means nobody's allowed to go to the store and then I'm working all day tomorrow and don't have time to go to the store. Is there any sort of plan b that you can use after 3 days? And should I take it even though I'm not comfortable with it bc I don't really know what it is or anything. Guys please help me I have no clue what to do.