Thoughts on opk's...

I have given up on using opk's for a couple months and was continuing with just bbt. I will be 33 in a week and my husband and I are ttc for our first since March. My cycles are pretty consistent at 31 days with ovulation on cd 15, 16 or 17, typically cd 17. I decided to do opk's again this month. I started yesterday, cd 9 and got low. Today on cd 10 I got high. I will continue testing until I get my peak. Just looking thoughts on success of conception based on solely opk's. *fingers crossed for my BFP for my birthday and Christmas*