Period 3 days late after chemical

Hi everyone!! Today I'm 3 days late for AF. My bb's are pretty sure but I've been having these weird...AF like cramps so I've been waiting for her to show up but nothing yet! I had a chemical last month on the 6th. My doctor said we could try again right away so I took my femara days 3-7. Got a positive opk on 2-22. Just so confused and so afraid to take a test just in case its a chemical again): Any of you ladies have a late period after a cp but get a positive opk on time??