Maybe baby??? Please read

I am on cycle day 39 of cycle 2 of TTC baby 2. I took a cheapo.88 test from Wal-Mart I waited a minute and it looked negative I threw it under the sink and didn't wanna look that was 2 days ago. Well today while cleaning the bathroom I got it out to trash it and it was faintly positive. I know it is invalid after like 10 minutes. Was wondering if it was worth retesting or just an evap? Any input greatly appreciated