I’m so afraid I’ll never be able to write a book because I can’t never come up with a plot. It’s always just scenes or characters or a setting, never the actual story. It drives me nuts and I don’t know what to do.
This is one of those things that requires practice. Additionally, it’s something that takes time (and not just because it takes practice). Finding the right narrative arc of a story is a completely different kind of creativity than putting prose on paper and like any other creative activity it requires a lot of experimentation, trial and error, and (most importantly) patience. It can take me six months to find the right shape of a plot, six months of moving scenes around and trying different story paths and different character arcs until I have an outline I feel good about. So this would be my first suggestion: before you start getting too deeply invested in individual narrative moments or set dressing, take some time to outline, and don’t rush yourself. You can’t force inspiration. You can encourage it, but you can’t force it. You’ll find a lot of advice about how to plot/outline here and here.