Fortunately, since I've been keeping written notes of my progress (ie. this blog) I was able to notice that, as I played more games, got better in general, faster, more multitasking ability, and more strategic/tactical knowledge, I've actually gotten worse at ZvP.
How the hell could this be? I watched pretty much every ZvP replay I've played, and...
Back when I started playing, the first 100 gas I ever got went to lair, always. I also tended to take my gas a bit early (around 12 or 13 supply). In ZvP this translated into me going 2 base 2 hatch lurker rush. When I got some lurkers, I'd usually move out to protoss' nat and just charge in, targeting cannons with all the hydra/ling I had while my lurkers settled in. If I broke in, I'd probably win, if not, I'd lose. I didn't really know much else to do at the time.
Then, one horrific and fateful day, I played some games on bnet. 4 games. All against Protoss @Python. And each and every time, they went 1gate tech to corsairs. As most people know, if you're unprepared when that corsair gets to your base, it can be gg pretty easily. It was very frustrating. That's when it all changed. Before that, my main priority was to get some lurkers and roll out. After those games, my main priority became getting hydras to deal with those corsairs.
Now, that's not exactly bad, but I didn't follow up correctly. What I inevitably ended up doing every game ZvP since then was getting mass hydra/ling, and since I was going mass hydra, I might as well get hydra ups, etc. This put a lot of strain on my gas econ early in the game, resulting in my getting lair very, very late. So late that I never had lurkers unless the protoss delayed his push for some reason. Since my macro isn't really strong yet, I'd get owned repeatedly by a group of +1 speedzeals and a couple templar, and then it was pretty much over. At this point, the only way I'd ever win was either via the occasional hydra rush, or, if the protoss for some reason decided not to attack when he took his third, and instead sat his army by his third to defend it while it warped in, my drop tech would complete around then, and I would drop my hydras in his main, forcing him to run his army back to deal with it, while a dozen speedlings shut down his third, and I took another expo. Repeat until I have cracklings and ultras. But basically I just lost to +1 speedzeals and templar over and over.
My late lair meant late overlord speed, which meant corsair harass was more effective for longer, and a couple DT could give the protoss map control ez. It also meant really late lurkers, which made dealing with the +1 speedzeals really tough. What a shitty way to play.
So anyway, I finally realized what I was doing wrong. Will I win more often now at ZvP? I dunno. But I'll be playing better.
tl;dr: The jig is up 'tosses. I know about your additional pylons.