I love Khan academy, but your brain processes things differently if you type it as opposed to hand writing it. I’ve had a lot more success mixing Khan academy with a common core reteaching workbook. They’re cheap on eBay and amazon.
Does your library offer free tutoring? Some libraries offer a ton of resources.
Can you take a math class at a community college? Sometimes in-person instruction is easier to understand. They’ll have remedial math; you won’t be the only one trying to learn it at your age or older.
Don’t give up on yourself. You’re worth it.