Wow. You need a lawyer for sure. The lawyer will have access to all the statements and offense reports and will have a better idea how the case will proceed. I can say that one cannot use deadly force against another's use of regular, nondeadly force. (So one cannot pull a gun out just because one thinks they are about to get punched in the face or because they got pushed.) If the bouncer pulled his knife and you saw it or thought you saw it, then you had the right to pull yours. That there were 3 versus one is not sufficient legally. And, it does not matter whether you swung it at them, etc. Brandishing it is sufficient (just as with a gun - you do not have to point it at anyone for it to be aggravated assault with a deadly weapon.)
You need a good local criminal defense attorney that can look at this. I agree with Ms. Henley, but I also think that depending on the type of bar and the bouncers' priors or previous complaints about the way they handle customers, you might be able to show the ADA this was an exaggerated situation that got out of hand or one that was not as serious as the charge reflects. Either way, you need a lawyer because as Ms. Henley notes verbal altercations don't justify pulling a weapon.
Although my intent in answering this question is to aid you in the legal process, my answer does not establish an attorney-client relationship in any way. You should seek the advice and counsel of a qualified attorney in your community to evaluate your legal needs and to advise you. No Attorney-Client Relationship is created without the specific intent of both parties.
Texas Penal Code §9.04 provides that "The threat of force is justified when the use of force is justified..... For purposes of this section, a threat to cause death or serious bodily injury by the production of a weapon or otherwise, as long as the actor’s purpose is limited to creating an apprehension that he will use deadly force if necessary, does not constitute the use of deadly force." So the production of the weapon alone, one could argue is not enough to make a case of Aggravated Assault. You should call a lawyer ASAP.