Maybe straps aren't tight enough or headrest needs adjusting? Straps should come out level with or slightly above shoulders. Does sound like a bad fit, head shouldn't flop forward.
I have a little travel pillow that stops this from happening it’s a life saver! My mum got it for me it’s a brand called kaklibin I think they are on Amazon they do lots of different designs and are around £10 🙂 x
@Tanya that’s not quite right, for rear facing the straps should be level or just below the baby shoulders, not above. His shoulder straps seem perfectly tight and correct position, his body is flush against the seat it’s only the head that hangs forward. I just feel the seat isn’t reclined enough, because if I fell asleep my head would fall forward too? Does that makes sense ahahah
The only other thing I can think is is he nappy to buckle enough? I wouldn't be happy with head flop at this age but I am no expert.
Saving to see if you get a response on this! X