20mg of diazepam is a pretty normal dose - It is high enough to cause panic attacks during withdrawal (I take 2.5-5mg PRN, no problems). Even if you were on it for a few years (Surely not 5-10 years), there should be no damage to your mind... Your psychiatrist shouldn't have put you on 30mg of Zyprexa (Cuz I think 20mg is the Max dose - And even 20mg is way too high and not worth the weight gain etc..)..

Thing is, I had 2-3 hour panic attack too (From overdosing on psychedelics in 2016-2017) - I had to take 1-3mg of lorazepam to kill the dissociation etc, calm down, and fall asleep.. Usually panic attacks resolve themselves - But I was afraid of my brain getting used to them.. The massive dose of olanzepine could have reduced neural connectivity in your brain, continuing your chronic anxiety (Or cognitive exercises for anxiety weren't practiced enough while on the lorazepam/diazepam - It's usually only advised to take benzos as PRN, otherwise anxiety gets worse long term).

I was put on 10mg of olanzepine, and it really helped for anxiety (More than benzos - Because it was over activated serotonin 2A receptors from psychedelics/involved in schizophrenia and depersonalization/derealization). I eventually was cured, and stopped taking olanzepine.

I wouldn't worry about damage to GABA receptors (Cuz the symptoms are the same as chronic anxiety) - It can depend on the dose (About 5 months - to a few years, or even very rapidly for some people - Taking one benzo can even change the brain chemistry in a bad way for many days or weeks/But it's not noticeable unless you're looking for those symptoms or perceptive distortions in reality). Damage to GABA receptors can also be determined by any other medications that you would have been taking, or still are on right now. Balance is important, and listening to your mind, body, spirit.

Here's some things that can help with anxiety;

"Cognitive Behavioral Therapy (CBT): This is a highly effective form of therapy for anxiety disorders. It helps individuals understand and change their thought patterns and behaviors that contribute to anxiety.

Mindfulness and Meditation: Practices such as mindfulness meditation can reduce anxiety by helping individuals stay present and reduce overthinking.

Exercise: Regular physical activity can improve mood and reduce anxiety through the release of endorphins.

Lifestyle Changes: Maintaining a healthy diet, getting adequate sleep, and reducing caffeine and alcohol intake can positively impact anxiety levels.

Stress Management Techniques: Techniques such as deep breathing exercises, progressive muscle relaxation, and yoga can help manage stress and anxiety."

^ These things really work for me - A few years ago, people didn't take this stuff seriously - But now the cosmic, spiritual energies have infiltrated into our collective consciousness, and more people will be meditating and such, learning more, and trying to be healthy - By helping each other, awaken...

Beta blockers are also underestimated in their effectiveness for treating anxiety (Propranolol and atenolol) - I take 50mg of atenolol every 12 hours - Helps with the shakes, decreases heart rate, physical anxiety, adrenaline in the chest, freaking out etc - If you're on a beta blocker (And you're not having dissociation), anxiety can be good for you.. Better than slow thoughts from weed for example, means you're smart and can worry enough, use that to your advantage if you tweak your thoughts enough, like a super power.

But really, you have a lot of anxiety conditions, you're super anxious... It can be fixed though with the right meds and decisions in life... Hugs though, I hope it gets better soon (: