We're U9 but U10 feels so good we play U11...and U12

Spencer and IV play in a soccer challenge league.  They are eight and nine but play up a league. Although they should be U10, we have them playing in U11 tournaments. Their first two tournaments, including the one this weekend, had some U11 and U12 combinations.  Kids at that age take a massive growth spurt so they really outsize our kids!  Plus, this is our first year in the league, and although our boys are good players, they are new to the 3v3 format--and it has been quite the learning experience.  That's the polite way of saying the poor kids are getting whipped by bigger, more experienced kids.  But it's good for them-- after this season, they will have lots of experience and toughen up, right?