5 months - tiny no more

baby has always been bigger than most babies her age. no, make that bigger than many babies who are older than her - 5 month old her could easily pass off now as a 7-8 month old. but what has struck me recently was how much she has grown and how big she is compared to when she was born.
now, she is barely fitting into her play mat lengthwise and one roll gets her from one side of the mat to being scrunched up against the other side of the mat.
where did my tiny baby go?