Minh, I admire your persistence! Since I live in Seattle I'm not much of a resource for suggesting teachers in your area, though.
However, while you are searching you might want to look at the Tony Ryder book on figure drawing:
Ryder, Anthony,
"The Artist's Complete Guide to Figure Drawing". Watson Guptill 2000
It's the best drawing book I've ever read and comes highly recommended by many other portrait artist pros too. I know if you practice the exercises in it you will progress a long way toward your goal, while waiting for a teacher.