How my games go:
A "standard" TvZ for me goes something like this:
I open 1rax FE with supp depot and double scout, simcity my nat with a bunker and supply depot, +1 5rax build, double scan Z once I get comsat. Unless I can see a fast hydra den with my scout, I invest like 700g or something into turrets ( 3 per mineral line, 3 on rax) then move out with my intiial force with stim, +1 and range on the way. I keep an scv on one main and scan the other to spot the Z third.
Now, if they go mutas I might be able to threaten their third if they've been skimping on units. If they go lurkers I generally can't do much. If I do take out their third while its building, they will take their third once they have lurkers on ramp.
Now this is where I either win or lose the game. I am either able to take all my units and bust their main because they have been greedy on amount of sunkens and units. If they have not been greedy, I am brought to lategame and I lose. If they have been greedy, I can win the game straight up.
I usually follow up with a factory for teching up to starport, put down 2x ports and start getting vessels. I lose often vs mass lurker, fast ultras, defilers before I get enough vessels with irradiate energy etc. If I do wait long enough until they have settled on 4 bases, I know for a fact I will lose the game because m&m + vessels will never win vs ultra/ling/defiler or what have you.
So with that last sentence in mind, I want to explain what I think about TvZ. T wins or cripples before zerg gets a big economy, if T cannot do this (Z gets unscathed to lategame); Z wins almost no matter what unless massive skill gap. So if that is true, my objective as Terran must be to win the game before that happens. How, I have no idea. Most zergs have enough sunkens at their main that no m&m army can touch it, go lurkers to easily secure their third and get defilers, fake mutas and go fast for defilers with spire tech, place out scourge to deny drops etc - I feel I lack direction, going +1 5rax push into SK terran doesn't feel effective at all, starting to build tanks after +1 5rax doesn't feel good either, not enough vessels and tanks are too late for any pre defiler timing. I just have absolutely no clue what to do vs zerg. It feels as if any decent Zerg will easily survive until lategame, at which point I just lose. So I need some sense of direction on how to kill / cripple Z before hive tech. I've tried +1 5rax and it doesn't work for me. I deny a ton of thirds, I win vs some greedy players, but most good zergs I face easily hold any +1 5rax build, and why wouldn't they, its not like its a free win.