A constantly changing schedule would be detrimental to me cooking, that might be the case for you as well. I need the oppressive clock to say it is time to cook dinner and if the time when I need to cook dinner keeps changing, I will forget to cook dinner and end up doing a quick meal of BS just so I can sleep.
You can also try meal prep, that is just to give you a meal that is as convenient as ramen during the week with a low daily time commitment. The idea of it may be kind of daunting, but it is just a bunch of smaller steps that you can AD4K off between without much issue.