Everyone is different so you just might not have enough HCG yet. Some women can test 5 days before AF is due and get a BFP and some have to wait until a week after. Try again in a few days. BABY DUST!
I think it's still too early for an accurate pregnancy test so you still may be pregnant. Wait until at least Monday to test (then it's 99.9% accurate) or Tuesday if you can.