Oh and Megan you are a good SISTER =) just think about it, take you time, but not much =) i know you will do the right thing if you should or shouldn't your still helping your sister, Take care of her alot because litle girls these days are being with guys who they don't even know really. Show her what you know, show her what she suppose to know to survive in this world. Don't worry about about it, she will understand, just that don't make her understand once the damage has been done, try to show her now that she's ok.
Hope my Advice helps you. Continue being a great SISTER. You do a great job at it =)