breasts are a bigger and sore, last period was june?

I have never missed a period before at all, but now i have missed three of them. my breasts are a bigger and sore sometimes, Negative result from all 3 tests. but no period a doctor told me in 1 of the test there was blood and i had a little stain of blood like brownish as if my periods were coming for the first time but nope nothing came. last period was june 2011