I don't know if this is advice you want to look into, but there are a few ways to do QCF inputs that make them somewhat easier. I also struggled a lot when I started playing with doing QCF but I learned to do it in a way that was more comfortable for me personally.
The easiest for me personally is to use the tip of my thumb, start by pressing down, and sliding it diagonally up to right. Don't try to press the three inputs individually its very hard to do, try getting the whole input in one motion. People who don't usually do this sometimes say it starts to hurt after doing it a bunch of times in a row but you get used to it very quickly.
Another way is to press down with the joint of your thumb (the bend point closest to the top, its hard to describe), and then kind of roll your finger down across the df and press the f input with the tip. Once you've pressed the forward input you have to lift your thumb off d+df so its just the top of your thumb on the forward. Its actually very easy even though it sounds complicated.
Also you can try to just press d with the same bend point in your thumb from the last step and do the same diagonal movement up to f, but this can be a little clumsy and inconsistent.
I promise if you practice and try to find the way most comfortable to you you will be able to do them very easily and you wont be scared of these characters with QC inputs anymore.
The main tip I can give you is to MAKE SURE you get the f input, I used to always not push hard enough on the f and it would linger on the df for too long. Push hard on the f input and you will see more consistency. Good Luck