No AF and Neg tests? TTC?

My fertile days were from Dec.8th to Dec.11th. My hubby and I BD a couple days that week. I started to experience severe headaches and nausea about a week later, as well as exhaustion. My AF was due on the 25th and still so sign of it coming. I took a HPT on the 24th and got a neg (w/ first morning urine) I also took a HPT on the 26th and got a neg (first morning urine) I have a 28 days cycle that is regular each month. I have never been on BC and do not have any fertility problems. We have been TTC for a few months now. Is it too early to test? We used Clear Blue Digital both times. If by Wed I don't get AF and don;t get a pos I am going to my doctor to get a blood test. Does anyone else have any experience with this? And it is not late due to stress or me thinking I am finally pregnant. I am being very calm and content this month with the outcome. Thank you very much and baby dust to all!