When you log on the Level 7 you see is your level in Google Play Games (assuming Android here). That is separate from this game. You need level 12 in XP in-game to take part, which you have.
When you start Alliance War you get 3 flags. When 12 hours have passed you get 3 additional flags. That is independent of resets. This is how it is from the beginning at level 12. Did you only get 3 flags all this time through 21 levels?
If you are not getting the additional 3 flags then that is a game support issue and you need to open a support ticket and send them screenshots of the issue.