BBT Staying high during period (not pregnant)

Hi everyone I’ve been having this werd problem with my periods and tracking since January. My BBT will stay at a high level until my periods over. This isn’t my only issue, my cycle now takes about 40 days, and I’ve been trying to get pregnant at this time with no luck. I’m seeing my obgyn in about a week for a pelvic ultrasound. I’ve showed them my charting before but they said its irrelevant to my cycle health. I’m not sure what to do I feel like the chart would actually get me help a lot faster if they actually looked at it. I’ve googled the high bbt and no one seems to have this problem without finding out they were pregnant the whole time. Has anyone else dealt with this?