Don't worry, it's hard to make look right even with bases.

Hell it's hard to make look right in a render, I remmber posing a (very badly modelled) character in a similar pose a very long time ago and the render looked off XD

It's just a hard freaking angle, you may have to revisit a few times (and I don't think any of us are going to complain about that XD).

If you really wanted to, you could line the rest of the body up with the face and have the gun vaguely pointed offscreen so it looks like she's just come to the rescue of the viewer and is shooting an antagonist offscreen, otherwise carry on as best you can and keep things in mind for next time :)