Period

So my period was late because I've been having so much STRESS! It's a long story but due to my Boyfriends b**ch of a sister causing me a lot of issues. Well I have a question if you have sex right before your period obviously protected will it cause it to be lighter? Anyway I'm spotting and not worried that I am pregnant just don't want the stress to put a toll on my body and make me sick or anything like that but it's starting off lighter than normal and I was told that it could be due to sex.?