Are you using Ancestral Swiftness? If you have the Hailstorm talent you need to keep up Frostbrand too. Use Boulderfist liberally so that you always have enough maelstrom to use 3 Stormstrikes, and Crash Lightning to buff your next SS.
Lava Lash is a last resort. I'll sit at high levels, using BF/FT/CL just waiting for that SS proc and I use LL very gingerly. If I'm capped out, it generally means I used my cooldowns at the wrong time. But in my current gear and with AS talent, I'm GCD capped pretty much all the time so I don't actually give a shit about a couple seconds of overcapping, because it isn't costing me any usages of abilities. You can only manage this though if LL is used sparingly, since Stormstrike and Crash both hit harder per maelstrom spent.
On cleave fights, Crash Lightning has a super high chance to proc Stormbringer, so it's not hard to get into strings where you open with FT, then just go BF CL SS SS SS repeat until everything is dead.