Doesn't matter which calculator you use, they are all wrong, even using the proxy for better profits you're not going to earn that much. The price could go up again which would be nice, but I think the days of quick ROI for mining gear have already passed, the difficulty is pumping.
That could be the reason why we just receive 80 - 90% of the Athereum from the mining pools as we expect.
Again,
http://karldiab.com/EthereumMiningCalculator/"The calculations accounts for average network blocktime, which increases accuracy but lowers predicted profit. Don't be fooled by other optimistic calculators!"
Also try different pools and proxies if possible. Some of them might give you surprising results.
i tried everything, but with my setup i only get not even 1 ethereum with 66 mega, when the calculator is saying 1.2