So I had my period last month (December) . It came on the 13 and was completely gone by the 15. I had unprotected sex on the 20. Its January now and I am 8 days late for my period. I have been super tired and my appetite has changed. I took a pregnancy test and I thought it was negative so I threw it away, and just for the heck of it I went back and looked at it and there was a faint pink line. Saying that it was a positive test. So I took two more test and they are negative. Im not sure what to think

No, reading them "later" does not work, they have to be done exactly as directed. Many will show positive a hour later

Next you are testing too early, you need to wait another week. You need to be at least 14 days late, to start testing.

Use first urine of the morning as soon as you wake up