Yes, that is all right. Of course, the thing you are thinking about or hoping for etc. must have been mentioned before. And then, there is another structure. Since a preposition can be used only with nouns, for verbs or subordinated sentences we need this structure as well. Ich muss noch über diese Situation nachdenken. (noun) Ich denke darüber nach, nächstes Jahr nach Deutschland zu gehen. (infinitive) Think about often translates to 'nachdenken über' rather than 'denken an', when we are talking about problems, difficulties etc., anything we must find a solution for. Ich muss darüber nachdenken, wie man das Problem lösen kann. (subordinate sentence)

I think about it = ich denke darüber nach Because: Ich denke daran = I (will) remember it Hast du dadran gedacht = Did you remember it? Hast du dadrüber nachgedacht? = Did you think about it? (Have you thought about it?) The rest is correct.