You will need a minimum of 12000 QAR to live with family in Qatar. Accommodation will eat up your salary to an extend of 4000 - 5000 in Doha, 2500 for your grocery and shopping, Child's school fees 800 - 1000 with transport per month, Car loan 1500.
What's left after all these!

Negotiate for more salary if you are qualified and if this is not ur last option.