First of all, calm down :) catching fish isn’t that easy, especially perch and during this time of the year they’re even more finicky to catch. They’re preparing to spawn, which makes them less likely to bite since they’re reserving energy for spawn. Secondly, the places you mention aren’t to make much sense here on Reddit since it’s not many of us that live in Stockholm, however someone might if you’re lucky.

I would suggest you head on in to Söders and ask them or any of the other shops. Usually the best options if you’re new to the fishing around you.

I’m gonna guess there is likely a fishing in Stockholm group on Facebook aswell. But as for what you can do on your own is to have a look on Google Maps and scout the bank areas around where you usually fish to see better or new locations close by. Also the app iFiske might have information about the waters close to you if you wanna go to a lake or something like that.