Test Again? or just skipped period?

Okay so AF was due on the 8th so I tested on the 7th and got a negative AF never showed up so I tested again on the 13th. Both tests were take him first thing in the morning with fmu and from the same pack and they were the off-brand Rite Aid brand, both tests also had extremely faint lines but I thought that was just the test itself and it would be darker if it was positive. AF still hasn't showed up what should I do? on the one hand I want to buy a better test but on the other hand I don't want to waste the money and it still come back negative.