Bbt question

Caroline
So I went off the pill in July and am still trying to figure out my cycle and when I ovulate. My cycles have been around 35-38 days long. I started taking by BBT a month ago or so, and am confused this month. On 10/7 (cycle day 28) I was 97.7, then after that went up to 97.9 for a few days then back to 97.5. I thought that might have been ovulation  since my CM was watery too. Then on 10/12 (cycle day 38) I was 97.7 again, and jumped up to 98.2 ad 98.5 for a few days after. Since it was a bigger temp jump, glow now says that when I ovulated. I'm confused now. I took ovulation tests back on 10/7 and it said I wasn't. Can someone explain the BBT process and maybe shed some light on my temps?