New to bbt

Sana

I bought a thermometer late so I started charting late this cycle. I’ve been testing early morning after getting 4 hours of sleep as well except today I woke up in bed took it and it was 35.8 and I slept again for another hour and then checked it was 36.1. Which reading should I trust? I didn’t get up, pee or drink a water. Also I keep getting negative opks. Is there any chance I ovulated?