Ok To Start My Period Was Two Weeks Late. When

Ok to start my period was two weeks late. When it did start it was brown for two days ,then very light red for another three days , then dark red for two days, now it's brown again and has been for two days. The whole time it was light enough that I didn't need a pad or tampon and only showed when I wiped. I would like to mention that I have very normal periods and have since I was 11 (I'm 20 now) so this is very worrisome. Do you have any idea what's going on?