What Causes Light Discharge During Periods And Cramps?

I was just wondering if it was normal to only have a period for three days and it was like a pink color. I always have really heavy periods, bad cramps and always last up to 7 days but never short of time and real light I also had all pregnancy symptoms and took a pregnancy test one came out positive and the other one came out negative. I have 2 kids already so I have been thru this before and I have been getting really light cramps since I ovulated.