black screen with white spinning wheel after High sierra login
You could try creating a new user account by tricking the computer to going through the initial setup process.

Instructions on re-running Apple Setup Assistant

By creating a new user this way you can check that the issue is specific to your user account, and not your installation of macOS. If this account can login you could copy the files from the other user and the issue is resolved.

If not then you need to find a better internet connection and reinstall, someone could download the files onto a USB stick for you perhaps?