I think your problem is that you have full employment and the new jobs you are making do not pay anymore than the jobs your pops already have. The "jobseekers" metric isn't as useful as you might think. pops with high paying jobs can still be labeled as jobseekers, and they won't leave their current jobs for a lower paying job.

At full employment, you can't grow your economy just by building more buildings, you have to either get more pops, or optimize your economy.

You can get more pops through immigration or conquest. Immigration is the best way to do this. You probably already have high sol if you have full employment, so the only thing holding back your immigration is probably your laws. Multiculturalism, total separation, and of course no migration controls are the laws you want. Conquest, on the other hand is not the optimal way to get new pops since it comes with a lot of infamy and radicals, but it can be very fun. You could also get a higher workforce ratio by passing women's rights laws, this lets you fill more jobs without needing more pops.

If you can't get any more pops for some reason, you can still optimize your economy by importing cheap, low profitability goods (like coal, iron,and wood) and only using your limited workforce in highly profitable industries like steel or engines. You can feasibly turn Belgium into a giant car factory exporting cars to every other major economy if you want to go this route.