The above is good advice, but don't stop Paxil or Lexapro cold turkey either -- they also have to be slowly tapered off of, especially Paxil. These are difficult drugs to use safely, and you need a doctor who knows them well. You also need to do your own homework so you can tell if you're getting bad advice. Good luck.
For what it's worth, .25 mg of Ativan is a very low dose. A standard dose is a 1mg tablet as needed, with the option of taking half if that's all you feel is necessary. So you've been taking half of a half dose. I agree with Paxilled that your GP doesn't seem well-versed in how much Ativan is right. I'm not a doc but I've taken my share of Ativan so I know how it works. My non-expert opinion is stop the Paxil and Lexapro, and take only the Ativan as needed. 1 mg for when things are rough, .5 mg when it's not so rough. Get some counseling to find out what's causing your anxiety in the first place, and learn some strategies for reducing or eliminating the problem. The ultimate goal should be to reduce or eliminate altogether your need for meds, it possible. Good luck!
First, you need a different doctor. It's always problematic to treat mental illness with a general doc rather than a psychiatrist you talk to first and believe isn't a clown -- psychiatrists can be pretty bad too. Any doctor who tells you it's okay to just stop Ativan, and uses Paxil as the first antidepressant to try, is a doctor to leave behind. Terrible advice and probably malpractice about the Ativan. It needs to be tapered off slowly no matter what else you do. But I'd also say, I don't think you've exhausted possible physiological reasons for this -- particularly if you have severe nausea as you say. You could have any number of difficult to diagnose conditions that might be causing this, from celiac disease to simple dairy allergy to all sorts of possibilities that need to be eliminated before you know you have a mental disorder. Again, you need a better doctor as a first step.