Maryland is a "may issue" state. Concealed carry must be justified; they don't have to allow you to.
http://www.handgunlaw.us/states/maryland.pdf
You are a small girl with a fair presence on the internet, depending upon how you phrase it, you would be justified to need some protection.
Don't listen to the machismo. Guys have pen15 augmentation tendencies and view anything short of a desert eagle as a chick gun. Anybody feeling tough can walk downrange and let Stace pop a hot FMJ in their a**; how's that feel?
9mm can be effective but bullet selection becomes more important. Like a small engine must be revved higher to keep up with a bigger one, the 9mm must move faster and open more effectively than a .45 to get the job done.
Stick with the 9, start with light loads and work up to hotter rounds. Concentrate on fundamentals and muscle memory. Accuracy is the most important thing and fine motor skills are the first victim of an adrenaline rush; you must be able to perform on autopilot. Even a 44mag won't stop someone if you can't hit the guy.
My wife has a .22 she is learning on and she is spooky accurate. If she ever has to pick up my weapon and protect herself, the kick will scare the crap out of her and she will likely only get one round off but it won't matter because it will hit where she aims it.
Be careful around guns, always treat them as if they are loaded. You may not get a second chance. It's a fun hobby but never forget these tools are deadly.
Powder residue on your hands does not make you guilty of murder. It's like having ketchup under your fingernails. Who cares? The important thing is you don't shoot anyone 
