How accurate are these?

I'm currently 10 or 11 dpo. I haven't felt too different, other than lower back pain for a day or two and sore breats (which I always get before AF). I'm gonna run out and get a pink dye. I've been testing and have getting  Bfn. So I'm just trying to be cautious and not get too excited. My questions is how accurate are these? Have you ladies gotten a BFP with these and it be accurate?