I have a 3 month old thats between 19 and 20 inches long, she eats a fuzzy (and sometimes a pinky too) every 5 days. She's grown about 2 or 3 inches in the past month and a half. Mine started on fuzzies when she was about 18 inches. My vote is to go for the fuzzies for Ruby.
Nick, did you try feeding her 2 pinks at a time, or do you think she's still too small for that? 14 inches seems so small, she must be adorable, but that seems so tiny for a 6 month old. Maybe someone with more experience can let you know what would be a good amount to feed her. But yes, the more you feed them, the faster they grow (as long as you give them enough time to digest, so they don't regurge it) ;-)