Temperature between ovulation and period low???

Ladies!
I have an urgent question,

I've been tracking my temperature for 3 months now. I use ovulation tests to pinpoint my ovulation. My periods and ovulation are pretty regular.

During my period, my temperature is low: 35.9/36.1
After about 2 days it rises to: 36.4/36.3
About 3 days after a positive test: 36.8
Right after that it goes back to: 36.3/36.4
It stays like that until my period.

Why doesn't my temperature rise in the second half of the cycle?

Thanks in advance!