Lea, a positive is positive. I don't think you can read much into the darkness of the lines. In my experience, if it is truly positive - it comes up pretty quickly.

I'd say congratulations are in order.

How late are you? Do you know your dates? You will need to visit your GP anyway for a referral to your pregnancy careprovider anyway so maybe you want to ask for a BT to confirm.

Good luck.
TICKLISH