working to tourist

need help! i applied for a job in doha in a local agency here. i have been done with the medical and stuff but after 6mos they cannot get me a working visa, they said i have to still wait. my bf who is in doha said i can just get a tourist visa and apply directly there. i can even get a better job and pay? is it ok to go there by tourist then have it converted to work permit? there are rumors that it is hard to get a work permit for a female worker, is it true? i am contacting my employer directly to see if i can just go to doha by visit visa then apply there directly so there will be no interference of an agency. what are the requirements and how long will it take for me to transfer from tourist to working visa?