Keep getting negatives.

Heather • Wife 3/28/15. Mother of 4 furbabies. TTC #1
I am very regular. AF was due on 7/7 didn't come so glow pushed it to today, still not here. I took a test last night and some thought there may have been a very very faint positive. Planning on getting more tests tonight. Does it matter the brand? Do I need to do it when I first wake up to pee whether in the middle of the night or if I sleep through the night (very rare)?