Shoe sizing problem?

ok so i went to the shopping arcade with my mom..and it is going on for 2 months before conservatory starts for me (9th grade) (im 14 years old) well In a K-Swiss shoe i ware a size 11, but contained by a Nike shoe I ware a size 9.5 and thats when my big toe is about 1cm from the lapse of the shoe...why is there such a difference between sizes surrounded by different brands..well anyway I bought the nike shoes within a size 9.5...and my toe is about 1 cm away form the shutting of the shoe..well these shoes are for the conservatory year..so im saving them for 2 months..in good health when i got home my dad be mad at me wreak he said my feet are going to grow by the time institution starts and my shoes will be to small to ware and i spent $65.00 for nothing...do you have a sneaking suspicion that my feet will grow that much within 2 months...my feet are already big ( 10 1/2 inches) so will they grow that much formerly school starts...is my dad rite in the order of this?? should i exchange them at the store for a 10 size (.5 bigger) ?
helpShoe sizing problem?
I suggest holding onto the taking and not wearing them until the school year starts. Then if they are too small you can other return them, if not next you just save yourself a lot of trouble.
You undeniably will grow, but at 14 (as a girl) you've started to slow down and your feet are nearing the size you will wear into maturity. Boys at 14 are still in the throes of growth spurts, but girls are slowing down. It might be that your dad is thinking along those lines.
First answer is right, though - hold on to the receipt and return them if they're too small.