It took me a bit of time to understand the premise, but I think I've got it...so this is a person who basically went to a public restroom to vent because she was depressed??
The writing does make sense in this light...but the idea is a bit strange, to say the least. So you're depressed, and you don't want anyone to see you...so you go to the bathroom and scream...?
Logically, it doesn't make any sense. First of all, if she did this for three years and that particular bathroom gained a reputation for being 'haunted', all she's doing is attracting attention to herself and increasing her chances of being found out. =/ Maybe it'd be smarter to go somewhere like, I dunno, a broom closet (or just go home...), and maybe not make a bunch of noise and speak out loud??
And second of all...how did she not get caught?? A bathroom is a small place; there aren't many places to hide...if it had stalls, she would have to be hiding in the ceiling or something.
And if it was just a one-room deal, then...why assume it's a ghost, when you could just assume it's a person having a breakdown (in college, it's not exactly unheard of...).
AND, if there was enough interest in this room that a group of girls would get together and exorcise it...no one thought to simply watch the room before it got to that point, and see if an actual human ever came out...? (She'd have to go back to class sometime...)
Unless they were "exorcising" it as a joke, and didn't really care...but the 'ghost story' atmosphere you set up suggests otherwise.
Basically, I can see why you'd be upset about it being misunderstood, but there are enough logic holes in this setup that I'm not surprised your test readers would get the wrong idea about what was happening. 'Subtlety' isn't really the problem, it's the events themselves.