Need help with my bearded dragon's age

I bought Bane on July 24th and the pet store did not know how old she was. She was 6 and a half inches so based on what I read I estimated she was about a month and a half old (im not sure if that is correct). She is now about 18 inches long. Would it make sense that she would only be 6 and a half months old right now at 18 inches long? I want to get an estimate on how old she is to make sure im feeding her correctly. If this is her age how should she be eating right now? I am giving her live feeders (either dubias or crickets) twice a day which i give her 10-15 per feeding so 20-30 a day. Plus i give her greens twice a day. I am confused because when i go to the pet store to get crickets and i ask for 100-150 they look at me crazy saying usually people only come in for 30-50 crickets at a time. 100-150 only last me about 4-5 days. Thats what makes me think maybe i am feeding her too much. Can someone please help?

Dragons grow at different rates - so as long as shes eating what your feeding her and shes shedding and pooping healthy which I am sure she is w/ the amount of food your feeding her and the salads shes eating that is great--- mine is about the same age as yours - he was born mid June and is now about 6.5 months old and is around 12 inches long and last I weighed him he was 67 grams - that was Dec 1st and I know he has gained more weight as he eats like a horse - but he was also the runt --- so I am thinking he is growing at the rate he needs to - he is constantly shedding - and I am also offering super worms 3 of them butter worms like 3 and BSFL as well to the staple feeder of dubia roaches - I have never fed crickets dont like them they stink and can cause parasites so I stick w/ the dubias and BSFL- dont worry about the pet store people they havent a clue as to how to take care of a bearded dragon - and putting them on a diet of 10-15 crickets per day is not enough for a baby - so just keep feeding the way your going ---
Karrie

My Figment is about 6-7 months old and would inhale his crickets if he could; 100 last me only two days or so, and would probably be on the scanty side on Day 2 if I let him eat all he wanted! Don't worry about what the pet store people say... most have very little experience with properly caring for beardies. Sounds like you're doing just fine in the feeding department (though I also am moving over to dubias because crickets can carry pinworms and other nasties; I still feed crickets mainly out of convenience in getting them quickly when I run out of BSFL and roaches).