Teratoma/complex cyst + small amount of pelvic fluid?

Hello all,

I've never posted to this forum before but in my frantic internet searches to reassure myself, have come across this forum three or four times now and it seems like a great opportunity to ask a few questions. So, uh, hi. c:

I'm 20 years old and I have a mass that either "originates from the ovary or is paraovarian." It is about 5 x 4 x 5 centimeters. It popped up on an unrelated abdominal ultrasound back in August, and I had a pelvic ultrasound and MRI last week (late October). The mass does not seem to have changed size since then. Here is what the most recent (pelvic MRI) report says:

"Primary consideration includes cystic teratoma.
Other differential considerations include complex cyst . Malignancy less
likely considered.  Given the size of the lesion, this puts the left ovary at
increased risk for torsion. If surgery is not contemplated, follow-up
ultrasound pelvis may be obtained in 2 months to assess stability."

So it's either a cystic teratoma (which I'm hoping for at this point - my mother had one, can they run in families?) or a complex cyst, and it mentions malignancy even though that's not likely (though in my worried little head it doesn't make a difference that it's not likely, it still scares me). I am getting an appointment with an ob/gyn to get the ball rolling, and get this thing out of me - I don't want a wait and see approach, I want it gone. It's just a matter of waiting until that can happen... :(

The MRI report also said,

"Small amount of free fluid in the pelvis with layering signal within it
posterior aspect , suggesting complex nature of the free fluid ,   and
presumably containing areas of hemorrhage and/or proteinaceous material within
it."

I know I'm not a doctor and most of us aren't, but should I be worried about this? Small amount of free fluid? I was menstruating when I had this MRI - could that mean anything? Can benign cysts cause free fluid?

One more thing... I'm jumping to conclusions because I'm anxious, I know.... but I read that one of the first places that ovarian cancer metastasizes to is the liver. I have very recently (due to previously mentioned abdominal test) been diagnosed with isolated fatty liver (meaning there are only fatty areas, the whole liver is not fatty). My mother has a fatty liver too, so I should be able to feel that the diagnosis is correct - but there is a small part of me that's screaming "What if it's cancer? What if it spread to my liver?"

Any help, reassurance, or suggestions would be really appreciated. Hope everyone is well. c:

[DC111]

Oh.. should also add that my cyst "demonstrates thin septation."