Definitely if you've been drinking a lot during the day not using your first wee of the day could be skewing the result a bit. It also may have been a little too early. This pregnancy I got my positive test the day before my period was due, but previously I've had to wait until up to a week and a half late.

The blood test should give you a much more accurate result, especially if your period is already late.

All the best hun, hope the answer is what you're looking for