I don't have POA but do have all the caregiving responsibility. How do I protect myself?

I can only hope that Sis would ever, in my wildest dreams, take care of either parent. She only does paperwork-stuff. She likes meetings, phone calls, anything that makes her feel important or in-charge, and demands that all of the kids follow her lead simply because she is the Eldest, so after all she knows Best.
However what the folks need, is daily CARE, time, understanding, sharing meal with them, take out their trash can, homebaked cookies, and most of all, come & sit with them for awhile, without expecting a reward of some type.
Sis will do none of that. She demands to be paid to come visit.
Its a sad situation but I fear is repeated many times in many families.

I think you and sis should talk to a senior services counselor to work out the care, responsibilities and discuss the trust issue over the caregiving. Is sister questioning your care? Expenses? If so, agree with psteg to request she care for dad for two weeks or 30 days and see how it goes. Then tell sis as POA, if she chooses to have sole authority then she can take over care. Usually POA is shared for financial and medical. At the very least the primary caregiver should have medical POA, while other sib could have financial POA but you must trust each other to carry out these legal responsibilities as they were intended.

PrettyGood,
If sis is in charge of caring for mom, then tell her to either take on her responsibility or your done. If she refuses to care for her, then go to the probate court in your county and file a petition for guardianship over both parents due to their incapacity or mental deficiencies. This is what I had to do to gain legal authority over my mother since my sisters didn't want any part of the caregiver responsibilities.

Ask her to trade places with you for a week and walk a mile in each other's shoes.