40 days

Tracked ovulation and we were active everyday during my fertile time including ovulation day. AF was due 3 days ago according to glow but still hasn't shown up. 
I'm now 15 dpo but still am getting bfns! 
I've been feeling very tired, crampy for the past 7 days, very thirsty, nausea on/off and tmi- diarrhea for the past 4 mornings. 
Is it too soon to ask for a blood test from my obgyn?