Car seat for a 2008 Pontiac G6?

My son has outgrown his infant car seat and I bought an alpha omega safety first from Sam's club that transitions from infant rear facing, to toddler fwd facing, and then a buster type seat. I have tried to install it, ive had the safety counsel, and the hospital but it just seems like we can never get it to recline enough. the angle of the seats and the space between the the fron and back seats and the hump in the middle just wont let it happen. The hospital finally installed it behind the passenger seat but its still doeant seem to go back far enough and his head goes fwd when he falls asleep. Does anyone know of a car seat that will work and can be in the middle?