Now, I did not say that, but, the odds of the machine being incorrect are slim to none. You may not have intended to drive DUI, but it is apparent that you did so. A decent attorney can likely minimize the impact through a plea deal, and there is always the SLIM possibility that there is a problem with the maintenance or the calibration of the device used for the test depending on the device used. An attorney can help leverage any possible errors into a plea deal if that is where you want to go.
Also understand that online calculators do not account for all aspects of alcohol absorption. They can't. We all absorb alcohol differently and at different rates depending on metabolism, food consumption, gender, body fat, etc. They also do not take into account when the alcohol was consumed in the calculation and generally assume an even distribution of alcohol over the time period you enter. In reality, most people do not drink evenly - they often drink heavily at the beginning or the end, and if at the end, then their BAC can rise quickly, but it drops at an even, relatively steady rate no matter what and this purge level is most often at about .015 per hour.
Many people also underestimate their alcohol consumption as one of the first things to go when you consume alcohol is judgement. There was research done some years back that indicated that many people that drink socially underestimate how much they have consumed by as much as 50%. That is not always true, but most of us tend to downplay or underestimate our consumption for an assortment of reasons, including fuzzy or unreliable memory.
In any event, you should certainly consult an attorney about your options.

