BBT still high after period

I seem to be having a bit of a strange cycle charting. I got my period on time or slightly early 11 days ago. But I never saw a drop in temperature as I usually do. It’s still holding pretty steady around 36.6C (97.9F) which is typically my post ovulation level. I have had changes in my external environment so I suppose that could be why (went on a long haul trip on holiday just as my period was starting). But I’ve travelled before and not had this problem. Anyone else experienced this? I’m worrying about how I’ll be able to see any shift this month. Charts below.