I had my period about 9 days ago but it was 3 days late and only lasted about 2 days when it usually lasts 4. My breasts have been extremely tender for the last 2 weeks or so and have been getting bigger. I feel sick at random times of the day with a headache and I'm always tired. I have taken 3 pregnancy tests. The first 2 were a week ago a day apart and the third I took yesterday(every single last one said not pregnanr) I am a stressed out college student so could this just be stress or is there a high possibility I am pregnant?