My bandwidth seems to be divided between upload and download

Depending on your bandwidth quality, uploading files may lower your downloading speed and the other way around. Explanation below:
When exchanging files with GigaTribe, control information is sent from the receiver to the sender to make sure there is no data loss.
So when you’re uploading a file, you’re also downloading control information; when you’re downloading a file you’re also uploading control information.
Part of your bandwidth is used for control information. This is obvious if you are uploading a file and then decide to download another one, you will see your uploading rate decrease.