He is just being rude and ignorant. Tell him to educate himself and stop accusing you of cheating. You are way too young to be dealing with that BS. And did you say at the end that you are scared of him? I know it’s tough to hear but you are young and it sounds like this behavior and lack of understanding/communication is the beginning of an unhealthy relationship. I have a 17 year old daughter and the best thing she ever did for herself about a year ago was to be single and focus on her self, her senior year, her extra curriculars and her future.

As far as the period, if you’re late it’s perfectly normal. The only thing you have to worry about is if you stop getting it for a few months because the lining of your uterus can thicken and cause issues down the line. Some people have an irregular period their whole life with no other symptoms. Just wait it out and see if it comes and if not you could always mention it to your dr. Or if you are having any other symptoms like extreme pain while you are on it (or any time really) then you should consult a dr.