Snakes don't typically eat their own shed... It's very abnormal, no matter how hungry they are.
2 weeks is nothing. Snakes can go up to a year without eating.
All snakes grow at their own pace. There is no set average. I have a 10 month old female sitting at 1400 grams. I also have another 10 month old female weighing 500 grams. One male is well over a year and only 400 grams. They all grow differently. As long as your snake looks healthy and has nice muscle tone, I wouldn't worry about 'what's normal and what's not'.
Housing multiple BPs in a single enclosure isn't recommended for non-experienced keepers. Just be aware of the consequences of housing two non breeding ball pythons together.
EDIT: WOW...did not notice how old this thread is...