I have trouble measuring my BBT at the exact same time every morning.
This gadget looks nifty since it measures your BBT as you sleep and you don't have to wake up at the very same time everyday. I just funded the kick starter. If it helps that would be great.
https://www.kickstarter.com/projects/1460153872/yono-fertility-friend-a-wearable-basal-thermometer?ref=hero_thanks