My hot sister

Every night, behind my [18m] wall, my hot sister [21f] lies in nothing but in tight thongs covering her juicy ass. At night, she presses the blanket against her gorgeous breasts and hugs it with her long legs, exposing her back fully.   

Once she came home after a party and all night, I swear she touched me every chance she got. She wore only a robe (she often does this at home in front of me) and she hugged me tighter than a sister should that evening. She also rested her bare, delicate feet on my arm when we watched a movie then. When she fell asleep, I saw her marvellous breasts under the robe, but I did nothing, sadly. She was so slutty all evening, damn it!  

Also once my sister was in hurry and ran into my room, as I has a mirror, and without even asking me look away she started to change. Out of decency I turned away, but I still took a glimpse of her incredible bust pulled down by her bra.  

Honestly, when I walk in her room at night and see her naked on the bed right in front of me, I get goosebumps. She always walks around in her robe so I always can almost catch a glimpse of her breasts or long gorgeous legs.   

Should I make a move sooner or later?