Mostly likely you had an xp booster that ran out

This. 

If that happens to be the case this game won't get another dollar.

What a joke for F2P. If you don't pay it's a snails crawl with events you couldn't possibly accomplish. 

You literally said in your original post, that you had the XP boost. So what's your complaint, exactly? That you ... didn't notice it had run out?

You can earn lots of XP bonuses thru in game activities.  I have something like 40 weeks built up now.  That said Raid is a very grind intensive game.  You shouldn't expect to be able to fly thru it and dont plan on being able to do everything, all the time as a F2P.