YA Medieval Fantasy with two sisters that are witches and take care of a baby wyrm

[Nallek]

That's about all I remember in the title unfortunately. I read it as a kid in 2005-2007 and it has a green cover I believe. The sisters name both start with a G too I think. Like Gwenyvere or Gwen or Gwyndolin. Something along those lines. The dragons were in the book were specifically called wyrms too if that's important. If anyone knows what I'm talking about that would be a blessing.

[Rainbowheart]

Does anything on the Girls with Dragons list look familiar?