Last week I did a sainsbury's pregnancy test and there was a very faint positive result so I got some of those cheap strip tests the next day and did them consecutively over 3 days and all 3 were negative. I then got some clear blue digital tests and did one and it was positive 1-2 weeks it said. Now it's a week later I've done another clear blue and it says not pregnant I am so confused. What is happening?!