Dear Jimy~
Welcome here to the forum. It's a good place to come ot get other people's perspectives, sometimes one is too close oneself.
I guss the first thing to say is you sound homesick. This can be a very natural reaction to a change of circumstances, particularly such a big one as changing countries. Australia has a fair few differences to the UK and there could be a lot to miss.
The second thing is you do not seem to have found -as yet - your niche where you have satisfaction and accomplishment here. It's a pity you do not see yourself has having done anything positive, though I suspect you are mistaken. Bringing up a family is a big thing in itself. Changing countries wiht a family successfully is another.
I'm not sure these constitute a mental health issue, though I'll stress I'm no doctor. I would think it a matter of degree on how much it affects your life.
There would be no harm in visiting a doctor for a checkup and see what they say. You are after all in charge and can weight up their words for yourself.
Are you trying to deal with this all by yourself or do you have support - possibly talking matters over with your wife?
Just as an aside I went back for a visit to the UK some time after I came out. I found things had changed and my memories did not correspond with what I found over there, so I was glad to get back here.
Then again Ronald Biggs (the Great Train Robber) voluntarily returned to the UK towards the end of his life being so homesick as to come back knowing he would face long imprisonment - it can be a pretty powerful feeling.
I hope to talk with you again
Croix
