OK, so it's been a while. I'm now in high silver and pushing for promotion into gold. Of the three matchups, the only one I feel comfortable with is TvP - I almost always beat mid to high gold players in TvP and have beaten a platinum ranked protoss.
My strategy is heavy bio with ghosts for EMP and a few medivacs and vikings mixed in. I do a fast expand build, usually a 2 rax, as follows
10 - Depot
12 - Barracks
14 - Barracks
16 - Orbital
17 - Depot
Keep making marines. Scout around for an early proxy pylon once you have about 5 marines. Drop a CC on about 23 or 24 supply, then add 2 more barracks and 2 refineries get stim.
Put 2 bunkers by the natural asap, which should be enough to defend a 4-gate if you scout one.
Eventually I get 6 barracks, 2 with reactors and 4 with tech labs, plus ghosts. I push out when my first ghost is done, during time which I add a factory and a third base, looking to get a reactor starport and an armory. The idea is that the ghost EMP plus stim should be enough to do serious damage with the first attack.
I just love the power and robustness of a heavy bio army with medivac support, and ghost EMP is a really cool ability to mix in. I would love to be able to make bio work in the other two matchups, because there I am really struggling to make any kind of impression.