I Googled for it - always a good idea - and found numerous references but not one of them was Welsh as far as I could tell. A couple were from the USA, but most seemed to be from New Zealand and Australia! Of course, I'm not ruling out Welsh immigrants.
No idea of the meaning, though of course
Phyllis and
Dilys do come to mind as similar-sounding names. It's a pretty name, worth following up and well worth handing on to future generations.