How to farm?

Hello! Started playing about a month ago. I play midlane. I’m not really confused about early game, I understand the general consensus is to shove -> roam to not miss any cs, but I get lost midgame and find myself falling behind in cs. I understand you’re supposed to side lane, and maybe it’s because im in a low rank (silver) but it seems a lot of the time waves are shoved super far on every lane and my team wants to fight even though objectives aren’t up. What do I do in these situations? Do I just roam with the jungler even if no objective is up? How do really good players maintain 10 cspm while roaming and even in games where they are winning lanes and waves are far away? Do I just walk to the far waves?

Thanks in advance.