I'm still not sure that there are at six month olds who are physically too big / heavy for someone who hadn't got any health issues to carry, though, assuming a decent carrier.
Am I carrying this child for 10 minutes, an hour, all day?
Am I carrying them up a hill, on the flat, over rough terrain?
Am I also carrying other things?
Am I large, tall, short or petite?
Is my baby large, tall, short or petite?
Although in good health am I an active person normally?
Am I carrying in good weather or poor weather?
YABU and more to the point, why does everyone have to justify whether they carry their child or not.
Does 'because their too heavy' have to be questioned?
Surely its polite speak for 'No I can't be fucked with carrying my child as I have a perfectly good pushchair. Now fuck off and stop trying to harass me into using one because I'm really not fucking interested'?