Thanks!
That being said, martial arts is a chance to learn about fighting and the pain and suffering it causes in a controlled environment. That's something most men these days never learn, which you can see by how they threaten and insult people on sites like this.
For martial arts to study, you'll obviously be limited by your geographic region and what's available. Honestly, you should just try a whole bunch and see what you like and if you like the instructor or not. Good ones to try are boxing, judo, aikido, shorin-ji kempo, wing tsung, and most forms of karate.
I'd avoid MMA (Mixed Martial Arts) unless you want to hang out with roid juiced douche bags with no sense of honor.
In your case, I'd start with either aikido, judo, or shorin-ji kempo. All three of these teach non-violence, are very structured, effective, designed for small people, and generally run as non-profits or taught at universities. I recommend judo especially for women.
Finally, you need to avoid scams more than pick a good martial art. To be honest, at your level just about anything will help, but if you pick a bad instructor you'll be in more trouble than if you picked a incompatible martial art.
When you meet your instructor, if he's immediately trying to sign you up for long term contracts or sell you shit, then walk away. If he talks in religious terms, or talks too much, then walk away. Meditation is great, preaching is not. If he makes claims that are "magical" then walk away. Floating, levitating, mind control, are all bullshit. Ki, chi, "energy" are fairly common and alright. If it feels like a religion and the students don't think for themselves, it's a cult walk away. If you get "love bombed" when you first walk in, it's a cult, walk away. If there are tons of belts walk away. If you see the instructor get his ass kicked by a student then don't bother.
Picking a good teacher is far more important than picking a "good martial art". If it feels like a scam, then just trust your gut and avoid it.
In my experience, MMA people are not "roid juiched douche bags with no sense of honor." The opposite is my experience; the comradery, mutual respect and emphasis on hard work is what I enjoy most.
Don't generalize based on your limited experience.
It's simple to learn, for young people it will not even seem like a workout, but it's likely the most powerful of all the arts and it's integrated with a chinese system of medicine if you want to explore nutrition as well.
You can also study push hands, swords, and even beautiful fans[1], all very gentle and peaceful.
Also, once you start working out, your tolerance for pain is much higher.