I think that you should make a fantasy story about it and kind of make her be able to controll plants and nature as a super power.

dang, sounds too much like me. She should run into some strange, mysterious, thing going on one day as shes going to school, like a murder or something. And have to figure out whats going on. Which makes her have to come out of her shell. Thats what i saw when i read the description.

another thing you could do is just a simple boy meets girl situation she biking to school and bumps bikes with a guy and...
or she could be sitting in her first block/period whatever you call it and a new boy is introduced and he sits down beside her and ...
She is working in her garden and someone appears behind her she turns around to find a guy admiring her garden
you could have him originally have something in mind or just plain be genuine
and either way they become close and consider becoming intimate in a deeper relationship than just friends

You could always have a fatal attraction senario a film you could look to if you want to try this one is "FEAR" its a Heath Ledger film the actor that plays Grissom on CSI is in it as well.

The hide aways and parents working around the clock thing works with the two ideas i mentioned above. Personally if i were to go with one of the two i'd go with the fatal attraction senario way more to work with .
Which whatever you deside i still say you should check out the movie it could give some ideas.

One idea you could go with is she has a friend that is her exact oppisite whom drags her to wild parties or tries to anyways she could be a bad influence on Teegan and the one time she actually goes with her to a R.A.V.E. it goes wild and her father catches her. Or it goes wild and they get seperated and a boy takes her one way and her friend goes another with a boy..

The ideas are limitless for your character whatever you decide and to get the ideas flowing with her you could try doing things like roleplays with her to get to know her and some of the senarios could give you ideas just playing around. forenstance i have a gypsy boy named Béla whom i've been playing as in a RP i've gotten to know him quite well. Through the role play i've been able to add more dept to his character and learn from other writers the different ideas if you like later you could check out 3 questions if you haven't already and character cafe as well as other RPs blabla on the JulNoWriMo forums i've had a pretty good time with the various interactions with the characters of other writers

good luck