As POA for my mom who has Alzheimer's I used some of her money to move to her state to care for her. Can I get in trouble?

I am very sorry to say that yes, you have done something wrong; but I wouldn't say it if it weren't so important for you to get advice about what to do NOW. I mean, I really do appreciate that you have acted in your mother's best interests to the best of your ability as you understood it; and it isn't morally your fault that your common sense approach is... potentially going to get you in hot water.

The thing is. Everything you've done WOULD be fine if your mother had agreed to it in advance. But as it is, she didn't; and although it certainly looks to me as if everything you did was primarily intended for her benefit, the fact is that you've used her money to pay your rent and secure an apartment without any authorisation to do it, which is for your own enrichment (even if that wasn't the point of it), and for a POA that's a no-no.

They'll ask, for example, why you couldn't move in with your mother if you couldn't afford to get your own apartment. They'll ask why you didn't keep receipts, and what records you do have of expenditure.

Get professional advice. If I were you I'd look for citizens' advice or caregivers' support groups in your area and see what legal services people like that are able to recommend. You could also try asking the court for guidance - they should at least be able to tell you what kind of documentation you will be asked to produce. If you get stuck, come back and we can try to help you with online research.

Did you have permission from your mom to pay for your expenses?
Does the POA document stipulate that you could use her money on your living expenses? You didn’t necessarily do anything wrong because in this country, POAs can be reimbursed for their expenses and be paid a salary but it’s not Black & White, it all depends on your state laws and what the POA form says.

You don’t have a rental agreement or lease showing the down payment & monthly rent?