Actually 10,000 is acceptable for immigration when its just the wife.. They need 12,500 if you have 1 kid and this amount multiplies depending on the number of kids. If you are sponsoring just your wife and 1 kid, in my opinion salary is not an issue. It is the degree. Go over to immigration for meeting and sort everything out.
For attestation, you need to have Qatar Embassy Stamp on the back of your degree/marriage certificate or whatever document you have. Once you have this, all you need to go ministry of external affairs and you are done ....

If you don't have Qatar Embassy stamp on your degree, but maybe UAE or Saudi, goto Chamber of Commerce between C/D ring road, get it stamped and go to MOFA ...