If you are mainly seeking anxiety control, a prn benzo can help, but is more abusable than Seroquel. Have you tried hydroxyzine or buspirone? They did nothing for me, but help many. Also, some anticonvulsants can help anxiety. Gabapentin and pregabalin are notable and usually weight neutral.

If you want an alternative antipsychotic for moodstabilization purposes, have you tried Geodon (ziprasidone)? I found it totally weight neutral or even weight friendly. While on it as my only antipsychotic, I easily lost 40 lbs on a diet in six months, normalized my blood test results, and maintained most all of the weight for years, until less weight friendly meds were added. I took it along with Lithium, Lamictal, and Tegretol, which were weight neutral for me, as well. It wasn't 100% effective for my mania, but mostly, and that was confirmed. I was only weaned off after 5 years when I developed terrible akathisia, but those years were comparitively nice...and trim. Initially, it can be very sedating, and requires taking with food. The oversedation did completely ease over time, with patience. I took 160 mg (split morn/evening) most of that time. One generally starts on much lower doses. It can be helpful for anxiety, too.