Started making a weekly menu many years ago, while working as a nurse with shifts. Have continued the practise as it helps with just buying what you need and food wastage is extremely rare in our home.
I write the menus on the kitchen calendar which also has all the activities and social dates on, so it can be viewed by the family and be looked back over when looking for inspiration for meals to make. The other tool I have that keeps the kitchen running smoothly is a pad to write down things that you have used from the store cupboard and need replacing. i.e. coffee.
We always have food in the freezer and pantry to rustle up some food for unexpected guests and events that crop up to disrupt the menu. Don't worry, be happy and carry on cooking.