The health pickups that increases your max life should have a "+" sign drawn onto the center of the hearts, the others are healing pickups. They "should" work but there can be always bugs :D
i played through it twice and had similar prob about health pickup the 2nd time i can say with 100 percent certainty that i had taken 2 hearts but only 1 of them increase my health and anyway as i said love your asthetic and vibe and art
