Flashing Smiley vs Solid Smiley

Aly
We've been TTC for 4 months. This month is the first month I've used an opk. I started my opk on Sunday, CD 10. I got an empty circle on Sunday and Monday. On Tuesday, Wednesday, Thursday, and today got a flashing smiley. Today marks my CD 15. I usually have a 29 day cycle. I really thought today would get a solid smiley, but no :( Does anyone have any insight? Or has anyone gotten more flashing smileys than 4 and still gotten a solid? I feel like maybe my LH surge has already passed. Grrr! 😡
Thank you!