Hello. I have a sudachi tree in a container and have had it for about 3 years but I really didn't do any care on it. I never fertilized it and I never changed potting soils since the first time I planted it. But now I am starting to become more and more interested in growing citrus in containers so I want to start off by taking good care of my sudachi tree. I've done some research on the proper care of a potted citrus but literally every source states different things and its getting me confused. So I want to hear from you guys.

POT: So the tree is about 2.5-3 feet tall(picture posted in my other thread), what size pot should I be using? The width of the diameter?

SOIL: Right now I am using just a bagged potting mix for it. Throughout my research I learned that making your own mix is better. So can I just get a well draining potting mix from home depot and mix it with pine bark and dump it in the container? Is that a good potting mix? And please don't post Al's mix, I've already read that and I'm not planning to go that serious into container gardening, I just want to grow two citrus(sudachi and yuzu) that's it.

These are the two main points I want advices on.