stuggling with Mengsk

Playing regular mengsk lvl 54 in Brutal difficulty - Despite having it for a while, i still strugle to win games.

I typically rursh the imperial witness and its upgrade, then start with tanks or thors depending on comp. Yeah, i'm not using Aegis guard, but if it's a requirement to win, it sucks cause i don't like marauders units in general.

My typical issue is that the 20+ marines i constantly teleport on my tanks or thors get killed so fast, then my tanks/thors are naked and i have to go back to base. Replicate this issue multiple times in every game and you can see why i lose.

Anything major i'm missing? Any tip? Thanks!