Needing a little reassurance

Well ladies i am positive i had implantation bleeding on 5 and 6 dpo. The problem is today it has been 12 dpo and STILL have BFN:( is it possible that some ladies take longer to get their BFP? i have never had any bleeding before during my cycles. and we didnt have sex during those 2 days. Any opinions for me would be great. Thanks ladies...just patiently awaiting that BFP!