If my normal blood pressure is naturally low could the dr prescribe for me an anti anxiety medicine like xanax or lexotanil?

Risky.: Most of the anti-anxiety medications that you've listed (like bromazepam) are in the benzodiazepine class which can lower blood pressure further. If you really need anti-anxiety medication, you should 1st undergo evaluation by a psychiatrist; let him/her know about your low blood pressure. They can help choose a medication from a different class (like SNRI, perhaps). Good luck.