The word “after” requires 2 pieces of information.
… and after supper, I went to bed. ✔︎
… and after I ate supper, I went to bed. ✔︎
… and after eating supper, I went to bed. ✔︎
… and I went to bed after supper. ✔︎
… and I went to bed after I ate supper. ✔︎
… and I went to bed after eating supper. ✔︎
… and after I went to bed. X (This is wrong, because the listener is waiting for the the 2nd piece of information, for example “… and after I went to bed, there was a loud knock on the door.”)
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… and then I went to bed. ✔︎
… and afterwards I went to bed. ✔︎