spotting

So, this was our first month of ttc #3... I ended up spotting a few days before ovulation and thought nothing of it. Then a week before af I started spotting just enough to show up when I wiped but not fill a pad. I have now been having this for 17 days and I'm a week late for an actual period. I thought she was coming because it was really red instead of the light pink and brownish. I used a tampon and there was nothing on it. I've tested 3 times and all were negative. Anyone have anything like this happen before?