Indah loved her tummy too & that's how she'd spend most of her days!!!
she did commando crawl, but only started proper crawling at about 7.5 months!!!!
We have floorboards throughout our house & I think that made it harder as she'd slip all over... But she was crawling a bit at Mum's on her carpet before she mastered it at home as well...

She slaps her little hands down hard on the floorborads to make the sound!!!!