We've flown all over the world with powdered formula, three bottles, and dish soap. It's not a big deal. As other posters note, don't depend on the airline for the water, pre-measure (as much as possible) the powder, and be prepared to clean bottles in the lav if you don't have the disposable inserts.

Note that security *will* allow you to bring enough bottled water and dish soap appropriate for your flight length. Given you're going half-way around the world, that could reasonably be a liter or more for each segment.