really dark opk for 3 days

Heather • 26 years old. 💍Married to the love of my life and Mother to a beautiful little girl 🍼👶

cycle day 17. have been testing with opks for 3 days and they have all been really dark. period is due in less than 2 weeks.... can opks detect pregnancy? just out of curiosity of course. not getting my hopes up for anything.