BFP then BFN 2 hours later

Hi everyone, I'm at a loss, I tested today one day late, and it was positive, 2 pink lines. After not believing it and testing a couple of hours later with a wee i barely held at all and its negative!!

Could this be due to the fact my urine wasn't concentrated enough the second time? Been ttc for nearly 2 years and this is my first beam of hope!

Has anyone else experienced a BFP then BFN due to this reason? I'm going to test again tomorrow morning but the wait is killing me.

Thanks just feeling very anxious and stressed x