6 weeks late, negative both home pregnancy and blood tests

Hi my last period was in dec 03, it's now the 20th of January and I'm having cramps, breast tenderness and tingling of the nipples. My tummy had grown bigger in a way I couldn't button my pants anymore, I also have lower back pains. My husband also noticed that my areolas have darkened and enlarged a little, feel bloated and tired. Had an hpt a week ago, negative and a blood test yesterday which is also negative. I've been feeling like having my period due to the cramps for about 2 weeks now but still no period. Can anybody tell me if I could be pregnant? or is it something else? A response would be deeply appreciated. Thanks.