Help! Test says BFN, but unsure

Kimberly
Hi,
So I tested on 2/27 and 3/2, both BFN. I was due 2/29 for AF. Still nothing. Had light cramping around 2/27 which is why I tested. Today my boyfriend noticed my nipples have more of the little bubbles than usual and that my areolas are a lot bigger than normal. 
What should I do next? I plan on retesting Saturday. Is there any test you guys recommend? Thanks!