My period came 9 days early

My period came 9 days early without any indication. I have been super stressed with work and my sons father who I havent heard from in 5 years contacted me the Thursday. I did have unprotected sex with my boyfriend and he did pull out (not the best birth control). Also I am not a very fertile person, Starting this early is very abnormal for me. My age is 29. Please no negativity just curious if anyone has any idea why it started so early. Thank you.