Sweetie alot of women don't get their BFP untill much later look at this link, it shows the results women get at 9DPO..
https://www.countdowntopregnancy.com/pregnancy-test/dpo-chart.php?dpo=9
Now look here: https://www.countdowntopregnancy.com/pregnancy-test/dpo-chart.php?dpo=12
The amounts of positives are a lot more common, I've also heard bad things about the 10miu, not as sensitive as they state. was it an internet cheapie?
Good luck though, don't lose hope, theres still a chance for that BFP.