Can 考える be translated to "overthinking"?
It's more like "considering". If you're thinking of the difference between 思う and 考える, 思う could be equated to "believe" or "feel that it is so", where as 考える is more like "pondering over". There's a little bit of overlap in some situations, but that's a good base way to look at it until you see how it's used situationally a decent number of times.
edit: I meant to say that if you're intentionally looking to say 'overthinking', 考え過ぎます（かんがえすぎます）. If you're not familiar with it, appending -過ぎる to a verb stem or adjective (dropping the final い on い adjectives) means to 'over do' or 'do too much' of something.