I got a faint pos this morning should I test again on FMU or would I have enough HCG at this point?:?

Hoping it wasn't an evap... I wasn't paying attention to the time, though it was within 10 minutes, the line got darker as the day went on... sounds evap-ish to me... it's been 2 hours since i peed, and I'm hoping to make it to 4 hours and retest.. after getting what I hope was a faint BFP, would I have enough HCG in me to get another BFP at this point? I'm 2 days away from AF.