I don’t want to say that anything you did was “wrong”, but it seems that you went from a KJF stategy to a “save Russia from Germany” strategy.
If you want to KJF, then attack Japan and try to prevent them from gaining territories that will increase their income.
If you elliminated the Japanese fleet on UK1, then you did good…that’s something I don’t usually risk. In the situation you’ve described I think I would have used the Austalians to take New Guinea instead of reinforcing India. Combine that move with a US1 attack on the Solomons then you may be able to force Japan’s attention away from the mainland.
When I play the allies ,and want to put the hurt on Japan, my main objective for the US is Borneo…so I can build an IC there. And that has to be done as soon as possible to prevent Japan from becoming too strong.
In your future games I suggest you put the pressure on the “money islands” as soon as you can. If you can get those then you’ll cut Japan’s income and if Japan wants them back then’ll they’ll have to divert forces intended for the mainland to contest them.