It's better you and your Faincee do your Nikkah in Pakistan and then let him apply for your visit visa (extenadable upto 6 months) when he returns to Qatar. I don't know on what basis you can get a visit visa to Qatar without any family here. 

FYI, even after getting your Nikkah done in Pakistan and coming to Qatar on visit visa it won't be easy to obtain a Pakistani Visa for you. Qatar has blocked all Pakistani's visa's in here....So unless your faincee is influantual and is well connected you could struggle a bit. 

If you were a valid RP holder in Qatar from before and your Faincee as well then you would have to do a medical test and then go to court for your Nikkah and then thats all...Most Pakistani men are searching for Pakistani women in Qatar for ease of visa transfer....Thats all I can think of from the top of my head...Good Luck....