One more thing about the shredded fins, your decorations may cause it when she's swimming. I think those are plastic since it appeared quite colorful in your photos.
There are plenty things you can try but let's make it step by step:
- Separate her into another tank (smaller) with low water level (2-5 inches)
- Do not need air pump (the flow created may cause stress, Betta can live well without it)
- I did not see fungus signal on her body and fins however...