15 dpo and AF 2 days late? BFN?!

Margaret
I know - this is one of 100 posts but - 8 month TTC   I start AF like clockwork on the 17th every month. Puts me two days late. Took a test first thing this morning - BFN. No symptoms really - just creamy CM. Some lucid dreams, and tinge like cramping here and there... I know that tests might not work for almost a week after missed AF - but I have my annual Tuesday. Would a bloodwork test be able to detect it if Implanted 10 dpo ?! I'm ok with a two week late but 3 weeks is kinda heart wrenching!