Red bleeding, light cramps

According to this app I should be 6 weeks pregnant. I had started some light brown spotting a couple days ago, but nothing out of the normal. Today however, I was sitting down and started bleeding to the point where it soaked through my underwear and pants. The blood was red and lasted about 3 minutes. I have light cramping but it qas nothing really bad that made me worried. I called my doctor and left a message but I am waiting for her to get back to me. My Mom died last year so I don't have anyone to give me any advice. This is my first pregnancy and I am 20 years old. Any advice as to where I should go from here?