0. Try TwitchTest
https://r1ch.net/projects/twitchtest . Ideally you want a 100 quality server.
1. Multiple Game Capture sources are usually not needed, and can sometimes interfere with each other (scene: Talking). You can use the same Game Capture for all your games. If you change games often, try out the hotkey mode, which lets you press a key to select your active game. If you play games in fullscreen, use 'Capture any fullscreen application' mode.
2. You also have a bit of encoder overload. If it's an issue, set Multipass to Singlepass and disable Look-ahead and Psycho Visual Tuning. Those use additional GPU.
If still having issue with bitrate, create a restream.io account, connect twitch to restream and setup OBS for restream. If still having issues, post new log.