I✀m going to bed after I finished my work对不对

前半段对，后半段有点不对。
因为你在说你做完这件事（finish my work)以后要做另外一件事（going to bed)，所以finish my work 要用现在的形态，然后going to bed 要用未来的形态。
正确：
I'm going to bed after I finish my work.

I'm going to bed after I finish my work.
主句将来时，从句现在时。
主句现在时，从句根据需要使用任何时态。
主句过去是，从句用过去相应时态。

不对
时态不一致,这是英语语法中的大忌
正确的应该是: I would go/was going to bed after I finished my work.
或者是： I will go/am going to bed after I finishe my work.

I'm going to bed after I finished my work错了
我整天改这种句子的同义句的...（因为老师叫的,haha )
给你个例句：They went home after they finished the work.=They didn't go home until they finished the work.

所以.你这个句子应该是：I go to bed after I finished the work.

am 改成was,应为后面finished是过去时

后面最好用一般现在时

i'm going to bed after i finish my work.