I'm wondering about my RES, I've had him for about a year now at least and he isn't really all that much bigger. How often and how much are you suppose to feed them?
What size tank is he in..?
You are right about they eat more veggies and friut when they get around 7"+. And the fact that you might not notice how big it gets and how fast. I recommend taking a picture every month or so next to a ruler or something.
I raised a hatchling (1.25") and in one year she was 4". I believe that they start to slow that growth rate down a bit once at 4-6". Her diet consisted of (and still does) live feeder guppies (as many as she can catch), large freeze dried krill (1-2) and a pellets and/or sticks, once a day.
Remember, only feed as much as the RES can eat within about 15 min. any extra scoop out and discard.