the psychiatrist there has me on 20mg of lexapro (which I've been on for months and don't feel it's working-but she hasn't switched me yet) and 10mg of abilify.
If Lexapro still isn't doing after some months at 20mg then it is unlikely to and it should be switched to something else asap. Either another SSRI, or, IMHO, given the lack of response to high dose Lexapro, preferably a SNRI (not Effexor (venlafaxine)), or tricyclic antidepressant. It would appear that the Abilify (aripiprazole) isn't doing much either so that may need to be rethought too.
but I didn't feel much relief with xanax ER and the regular xanax is addictive
Xanax is not usually addictive, but produces dependence, as do antidepressants. These are not the same thing, unless you're willing to risk death rather than quit taking Xanax, as people addicted to a common painkiller
will. The regular Xanax is no better or worse in this regard than the ER version.
I don't want to tell her I ran out of my xanax because I'm not sure how she'll react, but I honestly don't think I want to take it anymore.
Quitting benzodiazepines cold-turkey is a very, very bad idea which can be potentially dangerous. It won't help your anxiety disorder either. You need to tell her asap.
I took my last pills Saturday afternoon, so I'm assuming my anxiety will be getting worse in the next day or so and I'll start freaking out again.
If increased anxiety is your only symptom then it may not be withdrawal. Most people experience a range of other severe symptoms (I suggest you don't look them up lest you begin experiencing them all).