rare late period

hello!!! I know there’s millions of posts about late periods on here but I need some kind of explanation to ease my mind. I’m 3 days late on my period and I’ve had no pms/period symptoms at all. my period is usually always on time. I had some brown spotting a few days ago but that’s all I got. I took a test yesterday and it came out negative but I’m still confused 😭 I haven’t changed anything in my diet, I’m not really stressed, nothing is out of the ordinary except my boobs HUUUURT so I just feel like I’m either pregnant or somethings wrong with me lol