This happened with a fresh database running for first time
so the one in your assets IS the most up to date database-file?
If yes, then you should get the 15 as result as the database was not existent at the first run.
Or not?
The point is that you DID MADE some changes to the databasestructure (ony your pc probably).
You need to remember all these changes.
Updated table x and adding field y.
removing field z.
whatever.....
In you app you then check the db.
If it is V1 then you need to run the changes on the device database too....
Update table x and adding field y.
removing field z.
whatever.....
You then set the version to V2 after all changes are done.