To be honest, it looks miserable to me but each to their own. $2k "spending money" between 3 of you is a tiny amount. Is this effectively your contingency money as well?? With a young and growing child especially, what about clothes, shoes, toys etc? And pension contributions? Home contents insurance? You've dropped the flights home amount....are you no longer planning to leave HK at all during the 3 year period? Are laundry, cleaning products, toiletries etc all coming out of your food / spending budgets?
Have you also considered the upfront expenditure when renting such a rental deposits, furniture, utility deposits etc etc or are you looking at that separately as an initial one-off expense?