No your offer is not way too low. For a basic teacher in Doha (or a substitute teacher), regardless of the level of teaching, number of hours in the classroom, subject, age, qualifications, degrees etc., the minimum pay is about 450 to 500 QAR/day (multiply that by 22 working days/m). Teacher's assistant, pays close to nothing.

Now depending on the institution, private, public, language school, American or British Schools, etc., salary can vary between 12000 to 15000+. At some schools such as the American High School, teachers are required to spend more than 8 hours a day on the premises.

Then you have to fight to get your allowances for housing/ transportation/ holiday tickets and medical fully paid by your employer. Good luck.