[H] ZvT in HotS patch 7

Know ya'll wanna hear about a struggling Zerg :P. 

So I'm currently Gold in HotS, though I was Plat in WoL and I've heard that might be a tad more accurate. I'm struggling post patch with marauder/hellbats. I tend to hit 3 bases, start going into infestor ling, see some mech and add some roaches, and then just die when they attack my third. Fungal growth doesn't do much against the high HP units (Infestors don't deal with everything... I'm confused and scared), and lings melt away to battle hellions leaving roaches to get eaten up by the marauder count. The Terran has been on two bases the two times this has happened.

I'm wondering if you've got any theoretical or practiced responses? Mutas would seemingly be good against the army, but a thor added in makes it awkward, as do mines at home. Maybe a Spawn Hosts build? - I admit I'm not very familiar with them yet, but I know the locusts are light.

Or maybe just don't build anything til Brood Lords :P.

Cheers in advance.