I expect that will be an on-going debate - what is or isn’t a Welsh speaker. An eye-opener for me was sitting in a pub in Llithfaen, Pen Llŷn, listening to dozens of young people chatting away happily in Welsh. It wasn’t that they could speak Welsh. It was that they did speak Welsh.
I once asked a tutor how much of her life was spent in Welsh. 90% she said. And for her children (aged 2 and 4 years), it was virtually 100%.
It’s often said that the huge difference (hundreds of thousands) you see in estimates of Welsh speakers from some bodies versus the official Census figures is because of the self-declared element in the latter, and the reluctance of some people to declare themselves ‘good enough’ to be Welsh speakers.
I live in Penarth (moved here from London a year ago) and LOADS of people speak Welsh - it’s one of the reasons why I am learning. Apart from the teachers I know (who work in Welsh medium schools and so they speak Welsh “for work”) people seem to speak it for pleasure and chatting. I love hearing it.
Everyone I know in Cardiff speaks Welsh 
Seriously, though, I had a conversation in a Cardiff shop (not a Welsh shop) with a fluent speaker.