Ovulation dip

Hi ladies!

So I took letrozole this cycle to help me ovulate and I went for a sonogram last Thursday. My doctor said according to the size of my follicles I should ovulate around Tuesday (today). The problem is I'm on vacation right now and my opk is still a blinking smiley. This is my first time really charting my temps, does anyone have any insight on reading my temps?? It seemed to take a big drop this morning but I'm not sure what that means. I also don't get regular periods because of thin lining. I'm going to call my doctor later and ask what they think! Thanks in advance! :)