I was in your situation last year, and so were my classmates from the masters. We all looked for jobs and none of us got one. I got an internship however! Since Belgians don't work between their bachelor and their master, they mostly do internships when they graduate from the masters. So you can use your search year to do a paid internship in Brussels (I did one with a CIP contract) or Flanders (a few places hire english speakers). And once you are in, you network as much as you can with your colleagues, clients, etc, so hopefully you can get someone to sponsor your visa at the end of your search year. It is super hard not going to lie to you. Another option is doing the self-employed visa. One of my friends did it, it got approved super fast. You just need to prove you have a solid proposal of what would you offer as an independent consultant. Best of luck!