Positive OPKs & tracking cycles— still BFN

Hi ladies, I need some encouragement. My husband and I have been TTC for the first time over the past 3 months. I’ve been tracking my cycles for months (5 months officially on the app). This past cycle I stated OPKs on CD 12. Finally got a positive 2 days in a row on CD 14 and 15. We DID on CDs 13-15. And I’m a little disappointed because AF came today. I was hoping it was implantation spotting but no, definitely AF. 😢 Making a game plan for next cycle. Any one else have this happen?