Hi, Emma !
It's difficult to find someone (cyber or otherwise) to be a motivational buddy. What tends to happen is many people start out with the best intentions, but then life gets in the way. So, don't feel offended if you can't find a buddy or if the buddy disappears after a few days or weeks.
One piece of advice I give to new members is this,"don't look at weight loss or good health with an all or nothing mentality". If the only healthy thing you were to do for yourself was to drink 8 glasses of water today, that's still a step in the right direction. Remember, you're trying to change habits learned over a life time. that's not going to happen overnight, a week, a month or even a year. Change takes time. thus the need to be patient with yourself and your body. NO ONE ever became a healthy eater overnight. it's impossible.
That's why you need to cut yourself some slack. If you don't eat right every single day, you're still going to lose weight. there will be days you eat more than others and that doesn't mean you lack motivation. Losing weight isn't about having will power or self control. It's all about learning healthier habits.
One thing I would suggest is joining one of the different spark teams. Do you like to sew ? there is a team for members who love to sew or cook or sing or read books. This team is for members who are age 18-24. Join it. it's a good way to meet new people you're own age. www.sparkpeople.com/myspark/groups_individ