I am only a silver player here so I hope some of this advice can help. I used to think about the game a ton like what build order I was going to do and all these cool unit combos I was going to get out to counter him and I found myself losing all the time because the best counter to a cute unit composition, as Day9 says, is usually making stuff and then going to kill him. More on topic I play protoss so I can't exactly translate this to terran but I worked with a top 200 player for a bit and the one thing he helped me the most on is being faster. Now this might sound dumb or impossible but it's amazing how much it helps. I'm still far from a great player but when I really challenged myself to think:

Am I constantly producing workers?
Am I constantly producing units?
Do I have enough buildings to support my income?
Am I using my racial abilities constantly (chronoboost, mules, larvae injects etc...)
Am I going to be supply blocked? (Still suck at this)

then when I started really putting more effort into each game it started working. If you can just push yourself a little harder you'll start to outproduce your opponent in everything (workers, units, ability to reinforce your army) and then you'll see that the composition or build order won't matter so much. All this is not to say don't go into a game with a plan but just go in like ok I'm going to 2 rax expand and then get a bio ball, rather than plan out every single unit and all that and you'll see you're going to hit 200/200 supply faster or have more income and all that so you will be free to do more things.

Td;dr challenge yourself to push your limits a little more and try to be a bit faster and soon you'll find yourself rolling opponents who used to be your skill with just pure might rather than lucky build order wins and such.