help please

My periods are very irregular and hard to keep track of. My last period ended on dec 8. Fast forward to yesterday morning, took a pink dye test and I saw a line but only with a flashlight on my phone. So I went to bed last night and woke up at 3 to pee so I decided to take my last test. Within the first 30 seconds it showed negative. I was so tired and could hardly keep my eyes open so I went back to bed thinking its negative again. I look at it this morning at about 9:30 and a line has appeared. I've never had a test do this before and don't know what to think. Going to the store later to get a few things and I'm going to buy more tests. The brand of this test is rexall one step pregnancy test. Thoughts? Evap line?