low body temp

I constantly keep having below normal body temps, 35.9 c° dropping to 34.5 and glow doesn't even let me track it. it just says it's not a normal human body temp, to retake the test. what's the cause for having such low body Temp? kinda worried here.

I have tracked my body temp for about a year now. once in a while it's goes up to 36.0 c° but very rarely.