Explain to me please.

Last time I conceived I accidentally used a opk strip and got a faint positive

Then I used a hpt right after, and got a faint positive.

I was indeed pregnant, NOW I'm ttc again.

I took a opk test (faint line) this morning cause I haven't got to the store yet to get a hpt.

This is where I'm confused, I had a late miscarriage (22w) 5 weeks ago. I'm waiting for Af and nothing yet, but I've had either watery, or watery & stretchy cm off and on for days, I'm not having sore boobs or anything, I'm tired a lot.

But, I've heard you can use opk instead of a hpt for pregnancy test. But it says the second line MUST be as dark or darker then the control line. Then what does it mean if it has a faint line? That means something right?