You are using the child theme which is a BIG bonus here because it makes this easier.
1. Using an FTP program, upload a copy of the header.php from the main theme
2. Edit this file and look for col-md-5 and change it to col-md-4 (about halfway down the file)
3. Look for col-md-7 and change it to col-md-8
This will shorten the logo container and then adds the extra space to the menu container for more room.