We are using disposable diapers at the moment. When I look at the inside of the diaper there is no evidence of urine until I look at the top of the inside panel on the side where the belly button would be. I see above that panel (not inside it) that there is some urine but it appears to be a bit deep yellow. Is this dark urine or is that just how the diaper happens to absorb? Please help because my son has dilated kidneys and I need to know if he is having dark urine. Thanks!