Hoping for BFP after BFN

Hi ladies! I'm 31, and this is my 8th cycle TTC #1. I'm currently 15dpo, AF was due today but so far it hasn't come. I tested on 10 and 13dpo but got a BFN
I usually get sore boobs a week before AF which then gradually disappears and AF will turn up. This cycle however my sore boobs only started on 11dpo (usually starts 5-6dpo) and it's still heavy/tender/sore-ish. I also had some mild cramping on and off the past few days but today there's no cramps at all. Which is very unusual considering AF is due. 
Do you think it will be silly of me to have hope for a BFP after two BFNs? Do my symptoms sound promising?