Blood tests are the most accurate way to test BAC. Alcohol affects each person differently and just going by general guidelines of how much alcohol will amount to .08 BAC isn’t very useful because of that fact. If you truly did only have 3 glasses of wine I agree that a .245 BAC would be unlikely, unless they were rather large glasses and quite strong. But I kind of suspect you had more than the 3 glasses of wine that night or the BAC would not have been that high. Not all people at a .245 BAC end up passed out on the floor and unable to remember what they did. Again, each person reacts differently to alcohol and general guidelines are not all that useful in telling you how it will actually affect you. You are free to have the blood sample tested yourself to ensure the testing was done accurately, though. That should be done by your attorney, and yes, you really do need an attorney for this.
Regardless of the BAC level, though, you have the problem that you admitted to the cops you had been drinking before you drove the car home (and probably admitted you were at a bar) and your driving was observed by witnesses to include swerving and that would suggest that you were impaired by the alcohol. Even if if your BAC is below .08 you may be charged with a DUI if the state has evidence that you had some amount of alcohol or drugs in your system and that your driving was impaired because of it. You could try testifying that your poor driving was only because you badly needed to use a restroom, but few juries will buy that, to be frank. They will wonder why you didn’t go before leaving the bar or stop somewhere along the way home to use a restroom rather than driving in an unsafe, erratic manner.
Get yourself a lawyer. It’s the best way to minimize the impact of the DUI charge. Perhaps the attorney will come up with a defense that will avoid conviction completely. Even if the attorney can’t do that, perhaps he or she can get a favorable plea deal worked out for you.
However this turns out, I would advise you not to drive after drinking in the future. No matter how much you drink you can get hit with a DUI so there is no such thing as a safe amount to drink and not get a DUI. Each drink you consume reduces your reaction time and ability to perceive events around you and increases the risk to you and others of being involved in an accident. I realize this is not a popular thing to say, but if you want to go out and do any amount of drinking then arrange some way home that does not involve anyone driving who had been drinking. The risks of driving after drinking, both in terms of safety and in terms of legal problems from DUI charges, makes doing that a very poor choice.

