Can’t upgrade from OS X Lion to newer

Hi everyone, so I recently wanted to reformat my 2011 Macbook Air as it had way too much junk on it.

Only problem is now I cannot seem to upgrade to any newer OS X from Lion. Ive read that I can download El Capitan and download Sierra from there, but for some reason my Macbook says that Im all up to date.

As shown in the picture below these are my specs. 

When I try to download El Capitan, I get hit with an error and another message saying that I need to update the app store. 

I check the updates tab on the App store and theres no updates available. When I manually search for updates I receive a message that I am all up to date. 

Has anyone ever encountered this problem? Any help would be appreciated.