Ovulation on letrozole

I m 36.ttc for # 1 for 6 months after a miscarriage in last April due to blighted ovum.i get periods ranging bw 24 to 28 days but have minor pcos.my cycles are anovulatory so dr put me on letrozole 2.5 mg. this month is second round cd 2 to 6 alongwith ovaboster.i m getting a bit ewcm since yesterday but today the opk shows this.what does it mean?any insight please tell what to do I m really worried n disappointed.