Banditt, I think I'm the perfect person to answer because I'm a gay male nudist who appreciates Frazetta and Heavy Metal and used to study martial arts. Keep foremost in mind that you control the world in which this character lives, both it's current state and its past history; therefore, the outfit she is wearing now is vital to her survival and is "normal" for her society or at least for her. You just have to get across to the readers how she learned that this outfit is the most functional in her particular world.
The simplest explanation is that it is a stone-age civilization where women typically go topless and space-age hardware is literally falling out of the sky on rare occasions, (UFO's crash landing) and this character will grab a Kevlar shirt the instant she finds one, unless she finds a freakin' Dune force field belt first. But it lacks elegance to say that random luck chooses people's gear in this world.
This woman is clearly not concerned about snipers, gunslingers, nor archers, because chest armor is primary against those foes. So the weaponry typically used against her either easily pierces armor or bypasses armor by, perhaps, attacking the nervous system.
Also she doesn't have any social/political/religious reasons to cover up, nor is there cold weather. On the other hand, maybe her society is female dominant and males are taught to cover up lest they get molested by females. Turnabout is fair play.
If this woman gets into a lot of knife fights, she would want good thick gloves, comfortable shoes, and nothing else to slow her down. But in that case the helmet better be strapped on tight and keeping her own hair from blocking her vision. Although in our world men go bare-chested while doing intense athletics, I think women with her figure prefer a sports bra for support. The helmet and heavy weapon don't give the look of a knife-fight kind of athlete.
So I gather that she is more of a calculating distance fighter. The helmet may conduct gigawatts of cosmic rays to power the heavy rifle to generate intense X-rays and other nasty radiation to cook armies in her path, whether they wear armor or not. And a helmet with that technology might have an invisible force field to replace armor and might get sweltering hot when conducting that much raw power.
I'd love to toss around more ideas with you.
Chip