Login problem - Minecraft.exe, Since registering by mojang.com (Account Migrated)

Since i'm registered by mojang.com, registered via minecraft.net,
I get the error: Account Migrated, use E-Mail as username.
But I would like to login via my normal account (that i dont have to type that long email).
Because there is a bug in my "TechnicLauncher" I have to type the whole time again my email. Because i cant login via my Username.
How to login again via my normal username?
Can someone help me. Or can this bug be fixed? (Not about techniclauncher)