Ok, so I got a very clear BFN, but it might be too early?...?

I'm around 10DPO, I think and I got a BFN. AF is due tomorrow but I think I may have had implantation bleeding today because I never get bleeding that's not accompanied by cramps. It only happened for a few hours and then it seems like there is nothing. I know people have asked this question before, but could the test be wrong? I mean I could still be preg right? I'm thinking if AF doesn't come tomorrow I'll test again with fmu on Monday. Today, I also tested at around 4:15 in the afternoon and only held my bladder for about 3hrs? I really want a BFP!! Are false BFNs common? Anyone ever been in the same boat as me?