Help me, I'm confused (Caitlyn Build)

I've been playing almost nothing but Caitlyn the past 3 days. Some games I do really good at now that I'm a little more familiar with her, other games I don't do so well because I'm confused on how to protect myself when my support is not present or is roaming (been happening a lot my previous games, and it's a bit difficult to bot lane by yourself). One more thing is I'm still having a little difficulty CSing with her due to her attack animation being different than I'm used to, but I've improved a lot. Most of my games, if I'm behind on CS, it's typically one of those situations were CSing is dangerous due to lack of available wards this season (Fighting Blitzcranks and Morganas without vision is hell, even when you're long range with a nice net, if you can't see it it's that much harder to dodge).

BUT, good news is I recognize most of these issues as simple mechanics, and take steps accordingly to do better.

I am, however, confounded. Someone told me earlier today that my build was bad? The only thing he said was that I didn't build Runaan's fast enough, which to me is kinda silly because Runaan's to me has always been one of those mid-late game items (unless you're Kalista).

Can someone please look at my recent builds in match histories to tell me how I'm building wrong? Cause I've found the build to be very effective for how I play Caitlyn, so I was confounded to find it was somehow bad.

And keep the comments of "Bronzie this" and "CS that" out of the conversation, I've spent enough time on forums to be well aware of these things, just help me out on this build order thingy.

Cause like really, I'm seriously confused how it's bad?