Advice

My period is 3 days late, me and my bf did have unprotected sex a week before my period. I do have a yeast infection that I just got medication for and plan to start using tonight. I’m unsure if that could be the reason for a late period but just Incase it is I am handling it. Today I’ve had very very little reddish brown discharge but other then that there’s nothing besides the discharge from the infection. I was planning to wait till the 18th to see if I’d get my period by then because my cycle does fluctuate a very little bit but to be 3 days late is slightly unusual