worried, but hopeful
With your girlfriend at least showing some interest in a firearm for self-defense, I'm hopeful; but with what sounds like a self-determined set of limits on it's availability, I'm worried.
Please, forgive me if this is only reiterating something you've already gone over with her, but:
A person is the most vulnerable when they're getting into their personal vehicle. Their attention is almost completely focused tightly into a tight cone encompassing the car door - and the goblin knows that. Such a redirect of awareness is precisely the window of opportunity the predator waits for, enabling a strike from beneath the vehicle with a stun gun applied to the foot, or a grab-and-yank to drop the person, disorienting them and signaling the second goblin to attack.
Many women who believe that somehow getting into their vehicle constitutes them becoming far more safe actually panic and fumble keys/keyless entry remote when menaced, creating an even larger empowerment to the predator - and the person is found outside the vehicle (if found at the scene at all), never having made it inside.
As a responsible individual would necessarily secure a firearm that is unattended, I have a concern about your girlfriend obtaining the firearm when the car door window is being smashed with a rock/hammer/crowbar (assuming she makes it inside) - the explosive shattering of glass is almost uniquely disorienting and elicits a powerful wave of fear with not only the sound and the involuntary protective reflex of turning the face away from the exploding glass fragments, but the ephemeral concept of the vehicle being a refuge, a zone of remarkable security is destroyed - exponentially increasing a fear reflex. And a focused, timely retrieval of the secured firearm is nigh impossible. . .
Your designation of her having small hands means she is petite in stature - and she likely has some ongoing awareness of feeling vulnerable in the presence of physically intimidating, stereotypical bottom-feeders; recognizing the acutely one-sidedness of any envisionable attack/conflict. To see her empower herself with tangible and legitimate confidence pretty much necessitates unarmed combat training - and soon, as well as in-depth.
That she is bringing an interest in self-defense to light may well signal that she (unconsciously or substantively andf definitively) deems herslef to be in danger - and even if only on an intuitive level, it is to be taken with absolute seriousness (and comprehensive, thoughtful action)!
She will only come to a full awareness of her strengths when she has been empowered to tangibly know her own effectiveness in a fight unarmed! Only then will she know from first-hand experience the reality of tactics, and the mandatory tools of the mind and body necessary to see her living with competence - and much less un-named fear and dread.
You have your work cut out for you; and I am worried, but hopeful that she and you can see her to the attainment of a reasonable, comprehensive skills set ASAP.
She needs to get padded up and into a ring, to confront her fears of attack and her lack of such skills, as well as to learn the techniques to overcome said fears.
You say that she dislikes the loud sound of firearms? That begs the question of giving her electronic muffs. To me, it also implies a dread of edged weapons (I have found the two to be congruent) - and that is a terrible vulnerability bourn of ignorance.
Small caliber preferences/pretences are a sure sign of a low threshold to pain, as she intuitively does not wish to inflict a disparate measure of pain to an attacker than would surely see her flee/quit, and that can be addressed at a dojo (I've been down that road myself).
Stay in touch, OK?