How do I obtain support to care for my mother?

If Mom has no money you can get her in home heathcare thru Medicaid or place her on Medicaid in a nice LTC facility.

Her SS should be going to pay her bills. What she can't cover than you can pick up. There is help with Utilities and I would look into this now. Especially with heating cost. There's a timeline to be able to apply. If she owns her home, has she taken advantage of all the Senior discounts concerning her taxes? Call Office of Aging to see what resourses there are.

You are not responsible for your mother unless you MAKE yourself responsible for her.
If you spend what you should be saving on your mother, then please don't expect others to be responsible for YOU when you face old age without assets.
You mother is responsible for taking care of herself and her bills. If she is unable to then you should help her avail herself of whatever help she can find through the help of the social safety net and governmental assistance.

You, as an adult, are responsible for your own choices.

Look like my choice is going to have to be a work from home job and / or a job that will give me the flexibility of being off when I need to through the family leave act.

In some states you can get paid if your mom is on Medicaid. So if she is not on Medicaid currently, your first step is to see if she can qualify for Medicaid. Your local Agency on Aging office can help you with that, and advise you if there is a program in your state that enables you to get paid. If she is not eligible for Medicaid, you are likely not going to be able to be paid for your caregiving. If that is the case, to get any relief you are going to have to pay for outside care to come in to relieve you.

Before you do make this sacrifice, think long and hard about what your situation will look like a few years down the road after not earning any income. Will you be able to survive after mom passes?

Do not spend your money. As POA you pay with her money and keep good records. Do not co mingle. You are also not obligated to quit a job or live with her. Your next step is Medicaid application for skilled nursing.
If you feel guilt or obligation then as an adult you choose how to live your life or screw up your own retirement. And many caregivers die before the parent.
Your only option is to call your local social services to check on funds that will not be enough