Get more apps (5+) in the store, at least couple have to look "business-y" - like real estate catalog, taxi order and tracking, etc. Stick some popular libraries into them: ButterKnife and Realm are easy and actually a must have experience, add Retrofit/OkHTTP later. With this set you'll be able to start contributing to corporate in a week or two after you'll get a job. Also learn basic stuff you are being asked about during interviews (Java collections; 5-7 most popular OOP patterns - factory, builder, proxy and facade, dependency injection; MVC and MVP architecture; usage of libraries I've mentioned above + SQLite; basic multi-threading).

And keep attend to interviews and ask to explain questions which you couldn't answer - after 10 failed interviews you'll be able to pass almost all of them easily because questions are almost the same. Also you'll learn new stuff which isn't obvious for a lonely programmer.

Note: I got most of the necessary tricks for team collaboration in a week - with maybe a couple hours of help/explanations total (the job was for a mobile banking app with 50k active installs btw, now it's close to 300k). To me required team coding experience sounds like a bs. Actually difficult part is to comprehend existing code base - it's overwhelming yet there are tricks/shortcuts which help immensely to see the links between classes and code blocks: Ctrl + click variables and methods to see source and usage, Alt+F7 (or F6?) to see usage, Ctrl+N to find file by name, Ctrl+Shift+F to search everywhere.