Hi, i will try to figure you out for basic expanses.

first of all minimum appropriate room rent is 2500QR per person, Water & Electricity bill about 70 to 100 per month.
petrol is 80DHS per litre, minimum food expanses varies from 1000 to 1500 per month. rest is entirely depends on your living status.

hope this will help you upto some extent.
regards,