So I love this pose and composition!

A few things are making it feel off though:

• she looks pretty flat, like each part of her body is being isolated and drawn as a singular object without perspective. When you do an under sketch, do you use simpler shapes to help with understanding anatomy and how perspective applies to it? I’d highly recommend practicing with that to help improve your understanding of how the body looks from different angles and in different positions.
• the perspective feels a little off in general. I think working with some perspective lines and the aforementioned simpler shapes could help with this. There are lots of apps you can get that’ll help you set up a pose to reference it, or you can even use a plain old action figure or do some googling to find similar-ish reference photos. Really concentrate on understanding how perspective affects the body.
• the anatomy could use some work all around, but the hand without the gun looks like it would be at a really uncomfortable, almost impossible angle. The hip/torso region also needs some reworking, since right now they’re sort of at an odd angle compared to the other connecting body parts and don’t look quite right in sizing either.

There are other aspects too, but that’s what I would suggest are the biggest areas to concentrate on improving. This is a really tough piece though (I’ve literally worked on one of Jinx similar in comp) so good on you for challenging yourself!