Thanks, kaykay - I hope you're right!
I'm actually kind of angry that all of my primary docs to date - from my pediatricians all the way through adulthood - have not given my birthmark a second thought. They merely note it as "interesting" and that's it; nobody's even breathed a word about anything like Klippel-Trenaunay or possible vascular issues. The only reason I'm focusing on it now is because my dad's wife has a tiny one on her face, on her left cheekbone, and she told me I should have mine looked at; had I thought it could be serious before, I would have done something about it much, much sooner.
Grrrrr, so frustrating!