Bfp or bfn?

Ok so I took a test early sat morning and got a very faint line ..I thought maybe the test was invalid...but I had test couple days before and nothing at all..do I tested again the next day but couldn't wait till morning and got nothing at all..so today I tested early in the morning and got a very faint line again ..I'm 12 days late ..could I on fact be pregnant ?..shouldn't they be getting darker by now.?