My little (not so light) man is only commando crawling and he is just over 12 months.
He has started to pull himself up onto his knees when holding onto the couch so I think he may skip the tradtional crawling.

Each baby is different and your little one is content not to crawl I wouldnt worry. I do know what you mean about bubs being heavy to carry though. Jordan is 13 kilo and gets like a led weight after a while.