BBT confused

Faith

So I took my BBT this morning and the first time I did it on the right side under my tongue and it was 97.97F, I did it a second time just for the heck of it under the left side of my tongue and it was 98.00F, it’s been at 97.97 for the past like 4 days, IF I’m not pregnant when is it supposed to drop? I start my period in 3 days...