Evap line or bfp!?!

So I am 4 days before period is supposed to start. Bought this test just because I’m anxious at dollar general.

Looked at it 2-4 minutes after peeing, thought it was negative, trashed it. Maybe 15-20 min later I was curious and peeked again and that vertical line was there, but more faint. It grew darker over a few more minutes until what you see in this pic. You can’t tell here but the line is definitely blue.

I didn’t even know an evap line was a thing until I saw how weird this looked and started googling!!

Can a positive test show up that late?!

Just want your opinions! I’ll be buying a more expensive test and trying again in a few days if still no period