When do I turn around the car seat?

[Guest guest]

My 17 month old son (Diagnosed with Leigh's disease)is finally

nearing the 20 pound mark. He has had his (toddler size, convertible)

car seat rear facing until now and does not really have any leg room

left. He's about to come back home from a lenghty hospital stay. I am

concerned that he should not be forward facing because he has so

little neck strength. Has anyone else encountered this problem? I'm

working with physio/occupational therapy to devise some kind of seat

belt for his head, but I'm not sure it'll really do the trick.