Positive vibes!

AF was due yesterday. She never made her appearance. We are currently ttc #4 so I feel like I somewhat know how this is all supposed to work. I normally start my period every 26 days. So today, I am 15 dpo. I took a test on Monday, the 4th & it was negative. I just got up for my first pee of the morning & tested again since I am now one day late & it says negative. I feel very frustrated at this point. With my previous pregnancies, I haven't tested until I was around 5-6 days late... Could I STILL just be testing too early? I have a lot of thick, white CM & no sign of AF at this point. Advice on what to do please! And thank you :)