Negative HPT's....IMPORTANT....Please Read?

Aunt Flo was due sometime between yesturday and tomorrow. No signs of her arrival. Have had signs that we finally achieved pregnancy but have taken 2 Equate hpt's (one on the 5th and one today) both negative. Doctor wants to do a blood test tomorrow. Have any of you continued to get negative hpt's but had pregnancy confirmed by positvie blood test? If yes, how many days past ovulation were you? I believe that as of today I am either 13 or 15dpo. I am debating on whether or not to have the blood test done. I am so depressed over the 2 negative tests and don't know how much more disappointment I can take. Maybe if I hear some positive stories from others that have been through this it will convince me to go. I appreciate any help you can give. Thanks a lot and baby dust to all. Also, what hpt's did you take that kept coming up negative?