Curiosity

So it hasn't quite been a full week since the day my period should have started and I've had a negative test at the doc like a week ago before some other testing and then I had a negative yesterday but I was annoyed so it was one of those cheap 87 cent Walmart ones in the middle of the day. 
Is it still possible that I could get a positive?
I had some spotting like Monday and a little Tuesday but no there is absolutely nothing.