Edit: I'd like to clarify that I'm asking: Given a phrase or sentence that pops into my head in English, how can I find out how to say that in conversational Japanese? Sorry about the confusion. I didn't mean that I want to replace all learning channels with a machine translator or dictionary. I want a supplement for specific sentences.
I've been using Duolingo for a couple months. I'm beginning to want to know how to say things I haven't learned there yet. But Google Translate already seems to diverge from what I learned.
For example, Google Translate says...
...but I learned it on Duo as 日本語が話せます.
I get dropping the "I," but the が is different and also the し.
Is it because Duo is using vernacular? And either way, what online translator or translation method would help me find out a Japanese phrase or sentence, the way it's spoken between same-age groups and friends?