As a former Trust Officer and an Estate Administrator, let me give you the tips to make this simple. It appears that you have an estate that has some equity, but maybe cash poor. At any rate depending on the State you live in you will first go to either the clerk of court or the probate judge court's office. You will let them help you with everything you'll need to know and to answer your questions. They do this every day and will be able to tell you what to do first, second, third, what order the State aligns any heirs in an intestate settlement etc. You do not need an attorney to charge you money with a small non-taxable estate. As far as signing anything ask the court, they can be trusted. That's what they are there for, as paid by tax dollar public servants...see!
Also, since she died intestate, you will be court appointed, (not needing the attorney -see) as the Estate Administrator. If you have to close any accounts, collect insurance, sell the property, the court appointment and the death certificate copies (you'll get those probably from the funeral home) will put you in the position to handle what you need to, and as I said the clerk's office or the probate office in your county you can call if you have questions as you get this under way. They will probably run a creditor/debtor notice in the legal section of your local paper for you, noting your name as the appointment of the administrator by the court's power to do in intestate situations. A month from now you'll be done with everything pretty much. If there is any expenses you pay for out of your pocket and then as you may find are able to raise cash from any savings, checking, stocks, jewelry (silver, gold), land and the modular liquidating as needed to be done, keep a notebook, and make sure you take care of yourself. The expenses of even copies made at the clerk's office are appropriately the estate's bills and costs not yours, so reimburse yourself. You may want to, depending on what cash or assets you find by going over everything, to ask the court for an appropriate administrator's fee for your time. You are really doing a job. So, by the notebook you keep and the ability to give copies of anything you note to the clerk's office for filing too, you are staying on the right side of right. Hope this helps!
Trust is a two way street. Do you trust your mother or do you question her judgment? Have you considered why she has you do the things she does or why she tells you what to do? If you are dependent on her support, then you have an obligation and responsibility to listen to her and obey in most circumstances. If you are a grown woman, then its like anything else, you take what you need out of what she says and then make your own decisions.
Once trust has been abused its very hard to repair. If you have screwed up in the past and she has every reason to not trust you, then its unrealistic to expect her just to accept that you can now be trusted. Actions speak louder than words. Keep your nose clean and do what you are supposed to with a positive attitude and she will again trust you. If you don't know why she doesn't, then ask her, politely and without drama.