please tell me someone thinks i shouldn't be worried

so my boyfriend and I had sex for the first time about a week ago. we used protection and didn't cum inside. my period was supposed to start yesterday and this morning I thought it started but it was white mucus instead. we both feel like there shouldn't be and reason to worry and that I'm just late but I'm still really scared and I don't want to tell my parents because they will literally, and I mean literally kill him. Haven't felt like throwing up (except yesterday morning when I swallowed too many pancakes at once) and my period had come like a day late before. I'm sorry about being descriptive I just thought it would help. Please give advice!!!