Yes... you are Pregnant,Doctors swear by home pregnancy tests,they are as accurate as blood tests and very Rarely there are false Positives,infact i havent heard of any.
Faint or not means your pregnant,mine was very faint.
Threason why it is dark after is because after 10 minutes it is adviced not to read the test as the a false faint line could appear.Should always read the time given on the box...never past 10 minutes..but because you said it was faint at the beginning and before the 10 minutes then Congratulations on your pregnancy