At six months, I suspected something, but was told again and again to 'wait and see', 'give it time'. If you think it is a possibility, push to find out. At my granddaughter's check-up the doctor wrote in her notes hypotonia but did not make mention of this. Of course after researching on the internet we became concerned. We did call the doctor and she said not to worry.
All children develop at a different rate.
Of course, I know this to be true but on the other hand my grandaughter does display symptoms of low development of her large motor skills. The internet information was quite disturbing.