Why is my cat misbehaving?

ive had my cat or kitten since she was two months old. When we first got her she used to always be by me, always stay in my room with me and actually SLEEP at night. Well right now shes seven months old and she tries to climb on things like china cabinets,when i hold her for more than 1 min she meows loud and tries to bite me, i don't trust her to roam the house at night so i keep her in my room and she knocks things over, finds things (plastic,foil,roaches) and tries to eat them. we spray her tell her no but we never hit her. why is she acting so bad and different? oh and we all go to school so were not with her from 6am to 4pm.