There are also different sorts of self-centeredness. I think the word "selfish" implies actively taking things away from other people. There is an implicit cost of being a selfish person and it means you don't care about the needs of others, but take from them to gain something yourself.
I think the term "self-centered" tends to be seen the same way, but I see it as a broader definition. I've known self-centered people who were very kind and even generous, but they tended to live most of the time in their own little world neither taking or giving that much, so their life wasn't based on constant transactions with others, whether giving or taking.
I have a sort of dichotomy here where I can get overly swept away into the needs of someone else, or close myself off into my own little world. I don't have as strong a need to have social validation, so I don't need to have exchanges with others and have them tell me how kind or generous I am, and so I don't have the same motivation as people who need this a part of their identity. Please know that I think people who do need that are very helpful and good in the world. I don't mean that it's bad just because they get something out of it too. That's good.
I think i am a little self-centered, actually, but I think I am a kind, generous, and well-meaning person, but unlike an extrovert or Fe driven person, I'm not always involved with people for good or bad, so I don't do as much good and help as they do. I am more often lost in my own funny little world, and I can be oblivious to others, but I also don't ask that much of others, so my inner ethics are consistent. I also try to give something to the world through creating art, so it is an expression of that solitary little inner world, and a way for me to connect without connecting.
Edit: The times I've gotten very swept away into the needs of someone else, there was always a sense of trauma and emergency. I gave it a name, "panic attachment" because sometimes it was ongoing relational style and not a single incident.