Apart from: I wouldn't say that I was maximising others utilty. I'd say I was maximising their happiness, freedom, fulfilment, etc

I think I understand. I tend to use the word "utility" to mean something like "the sum total of everything a person values." Your use is probably more precise, and closer to the original meaning.

I also get very nervous of the idea of maximizing utility because I believe wholeheartedly that value is complex. So if we define utility too narrowly and then try to maximize it we might lose something important. So right now I try to "increase" or "improve" utility rather than maximize it.