Definitely get what you're saying.. maybe don't buy a whole chicken.. boneless chicken breasts and thighs aren't very expensive and at that point you can just cut it up or cook then shred it. If you buy a large amount of chicken, you can freeze what you arent' going to use.
Also, for some things I do get premade.. chicken and dumplings might be one of those things for you.. I have never made it but I would imagine it's not the easiest thing in the world.. so maybe that's the things you buy premade.
But things like hamburgers.. those are super easy to make, and if you buy the couple pounds of beef and the buns, you will have meals for days
The idea is that you buy things in larger quantities that will stay good for a little while.
Freezer is your BEST friend. Like if you decide to make Chicken and Dumplings.. make a ton then separate it out and freeze some for another time. When you want to eat it again take it out, put it in a pot and simmer til it's cooked
Also, there is nothing wrong with not making things. If you are doing fine with that, then keep at it. I think your mother is just trying to help in some areas from experiences she has had. Produce is more expensive and not something to buy in bulk so keep that in mind too.