Can I use Mom's money from joint account for personal use?

Of course not. You endanger your mom's financial well-being if you use her money for your own needs.
Get your own account and put your money there, and keep your fingers out of your mom's. You can be on there jointly as needed if she became comatose, but otherwise, it is her money.

It is quite detrimental to both of you to co-mingle your funds with your mom's. Listen to Rocknrobin and open a separate account today.

Today, get another account for your own funds. This could prove to be a hassle if mom ever needs nursing home care and has to apply for Medicaid.