I’m sorry you’re going through this. As others have said, we can’t help you find xanax online or anything like that.
However, you shouldn’t anyways because very very rarely are street xanax or online xanax the actual drug alprazolam. Fake xanax presses are common, and are usually filled with a different RC (research chemical) benzodiazepine which can be extremely addicting amongst many other dangers. There have also been reports of fentanyl in fake xanax.
My advice? Take the 0.5mg for now (I know it’s frustrating), and build trust with your doctor. They will usually never prescribe a large dose at first. You have to “titrate” up. At your next visit, just say something like “hey, I had a panic attack and the medicine you gave me didn’t help that much”.
This is first hand experience. You’ve just gotta deal with the psychiatrist until they raise your dose.