[Next_rim]

Post a replay, the problem is most likely in your scouting and mechanics, not army comp.

I'm a diamond protoss, but I consider myself good at reading PvZ, so I might be able to help.

Normally I would tech up to burrowed roaches and mutas, and a few bases.

Although there is nothing wrong with either roaches or mutas, zerg strength lies in infestors. They are very versatile, and are good for any situation, be it harass, offense or defense. Any zerg ball without infestors is pretty inferior. Any late game zerg combo should have some.

Also, ultimate anti-protoss ball is something along the lines of infestor + broodlords + hydra. This is best dps zerg can put together, and is hardly stoppable by ground protoss. Normally, zerg would open with lings or roaches, then add infestors and corruptors. This is enough to survive most protoss combos, which allows to grab more gas and get broodlords and hydra for dps.

some advice to counter mass stalkers or void rays, or ways to stop observers for zerg.

1) Stalkers. Fungal+lings>>>>mass stalkers. But keep in mind that stalkers can be different - 1-base 3-gate stalkers, 1-base 4-gate, 2-base 6 gate, 2-base 8-gate+2, etc.

Early stalkers are countered by timely spines, along with stopping drone production and pumping lings or roaches, either works in good numbers. The art of zerg here is pro scouting and build reading, then controlling greed and knowing when to stop drone production. Most zerg either die because of greed (not enough army), or because of panic (too much army). Signs of 1-base blink stalkers - early 2nd gas, low sentry count, no expansion. Don't rush to throw down spines though, because it can also mean DT, 4-gate or 1-base stargate. If you get an OL in sometimes at min 6, you should get an idea of what's up, and be able to react accordingly.

2) Late stalkers come about the time you get either infestors with fungal (preferable), or good numbers of hydra. Either works for repelling attacks. Signs of 2-base blink push - spinning forge, late gas at natural, low sentry count. OL or OS scout at 7-8:30 will usually reveal all tech. Also, keep lings at Xel'naga and at protoss natural, you will 100% see a push coming. Since protoss needs to secure a proxy pylon before pushing, you will have time to put up defenses.

3) Void rays in large numbers crumble to fungal and hydra. If voidrays are accompanied by archons, HT and zealots, you probably didn't macro correctly, and are behind on gas. Early voidrays are easy to scout, and you should have a evo chamber up early anyway. add 1x spore at each mineral line, and add 2x queens, pull all OL's back to avoid sniping, and you are all set, voidrays will do 0 damage.

As for muta, it is normally used to keep protoss in base, delay 3rd, while expanding behind it. Mutas in straight 200vs200 brawl are pretty weak. They are not your main dps, lings and fungal is. HT (and archons) shit on large muta balls, and 4 phoenixes with some stalker cover can own 10-12 muta. Remember - if you go muta timing, you have to either do enough econ damage, or expand heavy behind it, or take by surprise and win right there. Don't expect muta to win you a late game, they are not made for it.

Hope it helps. And, general advise - work on your macro and mechanics, it's more important at your level than anything else.

add: I forgot to address the observer issue. Observer = robo tech = colossi (or immortals). Which means, you need corruptors, lings and infestors. HT, archons or stargate tech is unlikely at this stage. Also, keep an eye out for blur, ususally you can easily spot observer movement, and use OS to track it down and kill.