clearblue - bad tests?

I have tested four times this month with clear blue tests - one lines and the other the digitals. I swear when I did line one, I quickly saw a + sign. that was the first test. the next three came not pregnant. however, I am now five days late. last week, I felt like I was getting flu (I heard some women feel like this before getting BFP) and had metal taste in mouth and was extremely thirsty for days! my breasts hurt on the sides and top but nothing major. i felt like my period was coming for three days around the time it was due. has anyone else had issues with clear blue tests? can I still be pregnant? thanks in advance and baby dust to all!