You should be feeding 10-12
small crickets every day at her age. Don't just put them in there and hope for the best, it is important to count them so you an monitor how much she eats. Also, if there are any uneaten free ranging crickets at the end of the day, you need to remove them or they will bite her in her sleep.
Supplements are
critical to her longterm health and survival. The recommend routine for jacksons is to dust all of her crickets with a calcium powder w/out vitamin D3 twice a week, with a multivitamin once a month, and with calcium w/ vitamin D3 once a month as well. It is important you go out and get these immediately (they are readily available at pet stores or online).
As we have already pointed out, the aquarium is completely unacceptable and should be gotten rid of ASAP. You need a full screen cage that is at minimum 16"x16"x30" for your juvenile, but you'll need 18"x18"x36" for when she is an adult, so honestly if I were you I would just get the bigger one to start. This is a commonly used, affordable, and good quality option:
https://www.amazon.com/Zoo-Med-Rept...F8&qid=1517242465&sr=8-4&keywords=reptibreeze
Your temperature is way too hot. A juvenile Jackson's basking spot need to be 75-80 degrees
tops (your girl is going to be absolutely cooking in there right now). This needs to be changed immediately.
All you need to measure humidity is a hygrometer... Go buy one, it isn't optional. Montane species need high humidity, so it is not good enough just to spray the cage and hope that's fine. With the substrate you have in there, all you are really doing is creating a breeding ground for nasty bacteria which could harm her.
Make sure to add live plants. They will help with humidity and make her feel more comfortable. She is probably so dark because she is being overheated and overall her environment is very poorly suited for a chameleon's wellbeing. Also, she is a chameleon and chameleon's are grumpy.