Is there a chance I could be pregnant?

My boyfriend and i are the most careful and usually rely on the whole pull out thing alone. My period is now 8 days late which isnt bad but i'm always on time. I have sore breasts, fatigue, nausea, and cramping but not bad like before my period always starts. I took a hpt when I was 3 or 4 days late and it was negative so i'm not too worried but want to be reassured