I agree with Nammu, the dose isn't likely to cause twitching.
I have high levels of anxiety and take mirtazepine (Remeron) 30mg to help with both depression and anxiety. I take it in the evening/night and it does help me sleep.
Maybe you could discuss this medication with your doctor?
Also, check our Dr. Claire Weekes' book/audiobook "Hope and Help for Your Nerves". If you can't find it at the library and want a secondhand copy, then visit abebooks.com. There are also YouTube clips available.
Hope you feel better soon... and do speak to your doctor about your concerns, asap...