Temperature still elevated after peak fertility

Hey everyone,
This is my 1st month TTC. My peak fertility period was Sunday 12/6 through Monday 12/7. I confirmed my ovulation was over this morning (just to be sure). AF is due 12/23. When I entered into ovulation this month my temp spiked to 98.1 then the next day dropped to 97.7, and then spiked back up to 98.1 and has remained at 98.1. Today it was 98.1 (no longer ovulating and on last day of being "most fertile" according to glow). 
I was wondering if it's a good early sign that my egg was fertilized if I continue to have a higher temperature than normal after ovulation. 
Also, do you count DPO from the day of peak fertility or the day after? I'm just wondering when I should take a pregnancy test.
I'm still getting used to all of the lingo on here and don't have a solid base to estimate what is normal for me yet. So any advice or experiences you have gone through would be most welcome!
Baby dust to all!