How can i tell if the OS actually updated?

How to download macOS High Sierra.

Also, try this:

Install El Capitan or Later from Scratch

If possible backup your files.

1. Restart the computer. Immediately after the chime hold down the CommandandRkeys until the Apple logo appears. When the Utility Menu appears:
2. Select Disk Utility from the Utility Menu and click on Continue button.
3. When Disk Utility loads select the volume (indented entry, usually Macintosh HD) from the Device list.
4. Click on the Erase icon in Disk Utility's main window. A panel will drop down.
5. Set the Format type to APFS (SSDs only) or Mac OS Extended (Journaled.)
6. Click on the Apply button, then wait for the Done button to activate and click on it.
7. Quit Disk Utility and return to the Utility Menu.
8. Select Install OS X and click on the Continue button.

About This Mac will be correct. Look in your Applications folder for Install macOS High Sierra.app if it is about 5.23 Gbs then the download has completed, you can double-click it to start the installation procedure. First it is recommended to make a copy of the install app prior to installing, put it on an external drive or USB stick as the one in the Applications folder self deletes after installing. This negates having to download it again should anything go wrong in the future.

As you are upgrading from Mavericks make sure any third party apps you use have updates available so you can continue to use them in the new OS. also check that any printers/ scanners etc have drivers and software available so they don't become obsolete under High Sierra.

When i open the app store it shows that high sierra was installed

Well, it actually is telling you that you have downloaded (and installed) the High Sierra Installer. You have to run the installer in order to actually install High Sierra. It is likely sitting in the background waiting for you to proceed with the upgrade, unless you have restarted since you downloaded it. In that case, it is in the Applications folder. Run it and complete the upgrade.