does this mean I'm pregnant ??!

If I am then I'm 15 weeks but I'm not sure because I've had 3 full periods with clots and all and my next one is supposed to be a few days away. But the reason I can't shake it is my boobs have never hurt before and now they hurt really bad. I've also put on e few pounds but considering the fact that I'm obese and my eating habits suck that doesn't surprise me and it's not too much to where my clothes don't fit so idk other than that I've had some abdominal cramping. I honestly don't know what to think. I've taken a test and it was negative. Please any advice will help