Hi Lan,
I take 45 mg mirtazapine daily - mostly in the evening with pregabalin to help stop the waking anxiety thing. It works to the extent that I don't wake to feelings of anxiety or impending doom like I used to. However, I still get waking nightmares, which I've had in varying forms for decades (a kind of post-traumatic stress problem from childhood family problems).
But on balance things are much better now than they've been. As Leunig (a cartoonist in Australia) says: "The whale of despair in the middle of the night turns out to be a sardine on toast in the morning" (I'm probably misquoting a bit).