Re: smaller babies in convertibles
The problem with baby's head flopping forward (so her chin is on her chest) is that it can compromise the airway. An infant who has good head control (can hold their head up, sit alone, etc) would be able to move/adjust their head position on their own.
From that pic, there's nothing at all wrong with the angle of the seat or anything. If she's not complaining about it (ie. she is asleep, so not complaining) and not moving her head to get comfortable, just let her be.