First full month using opk. Got them in the mail late last month and swear I got the end of a surge but again, I don't know because I am not used to them just yet. They were dark around 3 days after really wet cm and they were dark but not as dark as control until the line just disappeared over time. This month I've been taking them every 3ish days until about cd 11 (currently cd14) and yesterday around 5-7pm I took an opk and got a negative. Dh and I bd and this morning and I took another and it was my first positive. Both lines are equally dark, no mistaking it or guessing at it. Today at 5pm it was negative again.. is this normal? The post I see always have at least a solid 2 days of positives!