I've gotten pessimistic,
and I'm worried about something I would never have been concerned about before.
(私も悲観的になってきて、以前は決して気にならなかったことに不安を感じている。)

という文のsomething以降の部分について質問・・・
この部分の成り立ちは以下のような組み合わせだと考えていいですか？


Something concern me.

↓＋受動態

I am concerned about something.

↓＋未来完了形

I will have been concerned about something.

↓＋強い否定

I will never have been concerned about something.

↓＋仮定法

I would never have been concerned about something.