Pregnant or not?

Hannah • Mommy of an angel baby, a handsome 2 year old, a beautiful 1 year old and pregnant with our surprise baby
I've been having cramps, eating constantly and craving random food, constantly peeing and really tired. I have really bad headaches and get dizzy. I have heartburn a lot almost Everytime I eat and my period is a dark brown and is semi light. On my left side there is a mass, I took a pregnancy test but it came out negative..what could it be?