Update in case someone ever finds this: Took her to the vet. Evelyn had a abscess/cyst inside her pouch with almost 0.5mL of fluid that got drained out of her! Absolutely astonishing. I can't believe I missed it. They don't know if it's cancerous or not but we have a followup in two weeks and the vet is very hopeful of her situation. There was also some stones as well that they found that the vet is unsure of, but she thinks it may be from the body trying to fight the infection and not something else. Evelyn is currently home and on an antibiotic and antiinflammatory. They also agreed she is a very squirmy girl and taught me kind of how to restrain her to feed her the medicine because while she is a very good girl, she's very nervous (like her mom) and needed to get a bit of gas to calm down a bit for the Xray and first dosage of medicine. We opted not to do a biopsy today since she may not need it, assuming she recovers as expected in two weeks. However, the vet has a specialist she will reccommend if it comes to that who could also tell us whether it's cancerous or not.
Overall, I'm hopeful, and I'm absolutely glad I took her ASAP instead of waiting it out and hoping I could solve it at home.
I couldn't get a picture since she is like me where she hates to sit still, let alone if you're holding her. But the picture the vet took (I couldn't stomach to take it home. I felt so horrible looking at it) showed there was a big, black sac in her pouch area when you opened it up. They briefly sedated her with gas and were able to take a look at it and get rid of as much fluid as possible inside of it. I kind of envy anyone who has a glider that will stay still long enough for them to get a good picture with them, but at the same time, I'm happy because that's my Evelyn, just like me.
I may end up posting a followup update in case it turns out it's cancerous but otherwise, I'm leaving this as is. I hope whoever finds this post in the future, you're able to get the help your sugar glider needs. I'm glad I didn't wait.