So I just bought a previously owned, 4 month old female sugar glider last week and she is still overly aggressive. Her previous owners didn't treat her badly, for they had gliders of their own. I brought her home and the first couple nights were a little rough for her, considering she was still getting familiar with her surroundings, however, she is still aggressive. I feed her like I should and care for her as I should, yet she is really mean to me. I ordered a proper bonding pouch because the previous owner gave me a not-so-good, homemade pouch; still yet, I hold her in a roll of fabric that I've placed in her cage that has my scent on it. She doesn't crab at me as badly as she used to but she still gets ugly when I try to get into her cage. She has also recently started nipping at me through the cage and I don't know how to handle discipling her. I've tried touching her and bonding with her every way every doctor/professional has suggested, but I feel like she isn't trying/always feels threatened. I did my research before I bought her and I know how they're supposed to act but I feel like she shouldn't still be this aggressive. Any advice or input would be greatly appreciated.

One week is a very short time, so there's nothing worrying, some gliders are immediately friendly, others may take a lot longer to warm up.
I think you are trying to go too fast with her, take your time, try to not have expectations, because she can sense your frustration, and it makes it more difficult for her to trust you (would you trust a stranger which seems to be expecting much from you?).
Holding her might not be a good idea, many gliders do not like to be held and prefer come to you on their terms.

PLS do a search on your topic. This has been answered lots of times. The above post if accurate.
Gizmo took us MONTHS to tame and bond. Link has been with us almost a year and he still has his jumpy side, but is tame and doesnt bite.
Sophie was tame rehomed from day one. but her partner Big mama still doesnt like us but doesnt bit and we got her last november 8 months now. she would rather be all by herself.

each one is different and they all take time, MONTHS not days or weeks.