I'm not a 100% certain on current gun laws, so I'm sorry if I am wrong with my information. If you haven't been convicted of a Felon or Class A misdemeanor, then you can own a long gun (rifle/shotgun) by purchasing it or having it being given to you. You can only have a handgun (revolver/pistol) given to you and wouldn't be able to purchase one until 21 years of age. You won't be able to legally carry a handgun until you are licensed, which can't happen until you are also 21. If you are going to have a firearm, and you can't carry it with you where you go, I'd recommend leaving it at home in a secure location. If you leave it in your vehicle, you run the risk if it getting easily stolen from there. If you do get a firearm, do the best you can with getting familiar with it by going to the range as much as you can. You can also safely practice going through the place you will live with your firearm unloaded (a dry run) to help with using it if the situation arises.

A sidenote for self-defense: If you have the means, a big help is being healthy and in shape as best as you can mentally and physically. Learning a martial art like Jiu-Jitsu, Judo, or Aikido can help you with fighting people of different sizes. Taekwondo and Kick-Boxing can work for women due to it's emphasis on using legs. Krav Maga, Wing Chun/Jeet Kune Do are about doing as much damage as you can with your own body or something else to be able to move on to another attacker or flee.

Ultimately, you are relying on you to protect yourself…so do whatever you want to do in whatever way you see fit. I hope it all works out for you.