You are talking about saving an evarage of 3,800 QAR/month.
so..
flat 2 bedrooms: 7000QAR (very standard)
grocery = 4000 QAR (upper middle class)
electricity and water: 350 QAR
mobile bill (1 mobile): 500 QAR
gas for 2 cars (1 sidan and 1 four wheels): 550 QAR
medical: not less than 200 QAR
outings: depends on your style and standard, I'd say 1,000 QAR
nursery / school: 2000QAR/month
maid / house keeping assistance: 1000 QAR
vacation saving: 800 QAR
clothing: 1000 QAR
random and emergency: 1000 QAR
two cars: 4000 QAR (whether rental or credit settlement)
+ 3,800 QAR the saving you are targeting

so total?
27,200 QAR as total family package