Nachdem ich geschlafen habe is what i have so far.
And what you got there is perfectly fine :)
why nachdem? can someone explain it to me?
Try these links:
https://easy-deutsch.de/en/sentences/subordinate-clause/temporal-clauses/
http://www.canoo.net/services/OnlineGrammar/Satz/Komplex/Funktion/Adverbial/Temporal.html?lang=en
'nachdem' introduces a subordinate clause. 'nach' is a preposition.
hi world