Don't stream in too high a quality

Yeah, you either need to be a Twitch Partner (who get quality transcodes from the start) or have enough viewers to enable transcoding once you pass a hidden internal value (they don't advertise the specific numbers to avoid having unscrupulous people try to 'game' the system).

There's a reason the 'sweet spot' for non-partners is 720p, 30fps, 2000kbps. Maximizes your potential viewerbase while still maintaining a good quality stream.

Don't worry. I got lost in the 'MUST RUN 1080P!' fallacy when I first started streaming, too.
Just remember. No one will come to your stream for crystal-clear 1080p video. But people will absolutely leave if they get stuck in buffering hell because you're running too high a bitrate.