hiforever,
Unfortunately, you must be prepared for the fact that there are great chances that you may have lost your money.
The good news is you will not loose any more if you do not pay anymore. The law here does not protect you, the rules can change at any time and there is a great lack of transparency.
Investing in Qatar or in any GCC country is a huge risk as they are not sustainable economies, long run stable societies, the local climate won’t allow prosperity once the dependence on oil and gas diminishes and other regions such as Africa, South America and Asia will further develop.
Qatar's growth will achieve its climax just before 2022, after that it will go down the hill as all investments are solely for the WC 2022. Once that event will take place, the bubble will burst leaving Doha with its inhabitants and a few maids and laborers to attempt the maintenance of the overdeveloped empty facilities.

Lusail was a failed project since its beginning, born during a period of blind greediness inspired by the Dubai's "success" and just look what happened to Dubai!
Soon after 2008, once the world witnessed the beginning of Dubai’s collapse, Lusail’s project slowed down almost to its stop.
Doha city itself is oversupplied with residential and office buildings. There is just not enough people to fill in what Doha has already built and it continues to build with a population of only 350000 nationals. The rest are temporary workers like us who won’t settle here as we will never have a citizen’s status.
Last December when Qatar managed to get FIFA’s nomination to host the WC 2022, the project saw a (the only) reason to continue and it was reawaken. However it has been going (yet again) at a very slow pace and there are "internal" unsolved issues that will further delay its course.
It will go on (at least partially) just for the WC 2022 but it will never be what the brochures, placards and artists impressions have shown you!
Just look at The Pearl and see how many problems it has encountered and many more yet to come.
A final note, remember that buildings here in this harsh climate have a very short life span. A 4 or 5 years old building here, may look as old as a 50 year old building in a tempered climate.
After this brief insight, it’s up to you to decide but if I was you, I would rather invest in your own country. A progressive, successful developing democracy with great long term sustainable economic potentials.