Hi,guys!I just purchased my first Mono Speedy 25 today,and right now i have a second thought---may be i should have bought 30 instead.I am 5'7 ,120 lbs,i am thinking---may be it is too small for me????But the thing is i hardly ever carry anything in my purses---just cell phone and keys and wallet---so dont you think 30 will be too big for that???I dont know what to do???Should i exchange or should i leave it and start enjoying?????Thank you.