shimmied for congrats, not the dilemma!! i know you've worked for this, so i'm happy for you!
will your parents be financially funding this team for you? if so, their opinion matters... if not, well... you can kind of make that decision on your own now. not that you should ever lie or go against their wishes.
are their other people on your new school team who also do the i5? what's their practice schedule (1 day a week? 2?) what's their comp schedule? what's the cost? all of these things could drastically help your case with your parents. my guess is its cheaper with significantly less travel and comps. polar opposite of what you would do on a senior team. which they may not fully realize, since they're still in WC mode. success stories of other girls on the college team who have done both will help too. and any sort of carpool set up. you will always be their baby and they will always worry. especially if you're driving nearly two hours in the dark, late at night, in a place they are unfamiliar with and where they cannot just jump in the car to save you should you get a flat tire etc.
i hope you can make it work!! good luck!
