Alliance attacks

I got attack by an alliance most players were at least 2 lvls higher than me and I lost my fav sub city

This means that you were farming a member of that alliance, or annoying them some other way.

A common tactic of them is to steal their enemy's sub(s). This happens a lot, and there are a couple things you can do.

1) Spread out your subs all over the map so it'd take hours of panning around the map to find just 1.

2) If you see a non-neighbor attack a sub of yours, as soon as the attack is over you should consider moving the city.

It's all part of the game, and you'll get past it soon. Have fun! :D