Not exact science okay. But a 42% variance is a bit extreme, no? And it's been over a week like this. Honestly wondering if the 0% fee is being hidden. Just realized forgot to mention this is for RavenMiner.com pool.
I would try a different pool. I've mined at Ravenminer for a while. I earned about what the calculators estimated + - 10ish%, but my hash rate is a bit larger than yours. Same at Suprnova too. It's the smaller pools where I had better results - like RVNPool (closed), Threeeye (Closed) and now Virtopia.
Try a different pool on the same Continent that you live in. Ravenminer and Suprnova are the large pools. Yiimp, Panda, Cryptoparty are medium pools. Pickaxe, Virtopia, and minepool are small. Watch out for any pool under 10 GH.