Help with opk

I've been ttc #1 since last September. I had a miscarriage in January. And ever since then I've trying to do the whole "it will happen when it happen" thing. Although I do try to see when I should ovulate according to Glow. Anyways, this month I started to use opks. I've used them last year and I would get two lines for about two days and that's it. But it seems this time they've gone for 5 days. Is this normal? I've tested at the same time every day with in the morning. Could I be ovulating for that long?