Here's a suggestion that I'm only suggesting for you to try.
Get a big desk calendar to put on your wall (unless there are big wall calendars). Take a black ink pen and write down things you can do on certain days (example: Pay Bills on Monday and write the list of bills you have to pay that day, Clean my bedroom on Tuesday, cook a big supper on Wednesday...maybe even have leftovers on Thursday, etc.)
Then, find a blue pen or another pretty color you like that stands out (purple, green, etc....but not red). For each thing you actually do on that calendar, circle it. At the end of the week, make a note of the things you did and talk to yourself about the accomplishments you did. Your reward is actually seeing that you did do things that needed to be done. If you want a tangible reward, think on that too.
Now, here's the important part. If you didn't get to something that still needs doing, put it on next week's list (if you can
push it back...bills are tops on every list). Also, don't beat yourself up for what you didn't accomplish, simply talk to yourself about what you DID accomplish. Even if it is only one important thing that week.
At the end of the month, count how many things you did, see if you can beat it next month, etc. Just think about it. Seeing it somewhere in a visual place is much better than it going around in your head making you upset.