am i overreacting?

i (16F) live with my mom, grandparents, and uncle. my uncle has been kicked out once before for his drug use. he gets kicked out he acts like a child talking shit about everyone, my grandma calls him to help her out with the outside of the house and he ends up coming over once, twice, then every day and now he lives back here again. his drug usage is pretty bad as he literally steals stuff from my family members. there’s only been two but the first time the medication belonged to his deceased brother who had passed about two years since then. now he has taken medication from my tia. information for absolutely anyone to answer my question, i have my own bedroom and i don’t share with anyone. i am cleaning it today so my boyfriend can come over in two days. i don’t have tomorrow to clean it as i will be over at his house celebrating our six months. so i have to do it today. i am clearing off my bed and fixing it while i put my bedding to wash. i am fixing my plushies and i happen to find a lighter. see, i have taken lighters from my kitchen or something about once or twice. i’ve never seen this lighter in my life. i have the idea that my uncle may have been in my room already to which i quickly go outside to talk to my mom. i ask her if she’s been in my room recently, to which she answers no and asks me why. i show her the lighter and say this was in my bed and i have no idea where it came from. she says it seems like it’s been there for a while. she said it might be hers but she doesn’t remember ever having a lighter like that (it is a rambo lighter, my mom isn’t a big fan of the movie) and i just say oh okay thanks then and walk away and i end up texting her a couple minutes later saying, “i don’t get it though, i cleaned my room for my birthday so my boyfriend could come over and i took everything off my bed and i even moved my bed and i found nothing. have you been in since then?” to which she says “no, we will get a lock for your door.” am i overreacting or is it possible my uncle has came in here without me knowing? what is his business in here? when was he last in here? i usually am not home maybe like 2-3 times a week as i go to my boyfriends and when i’m not over there i just stay home. i don’t have a doorknob as a result of not being able to keep my room clean. i have learned i can shove a pencil into the door to close it. it’s only been once or twice that i have accidentally left it unlocked, but usually when my uncle is here he’s outside. so it had to be either that he came in that one time or that he learned how to close my door and now he just comes in. am i overreacting for being sorta paranoid? especially him being on drugs and in my house i just feel paranoid as to what and why he may be doin that for as well as if it’s true and i confront him what will happen then? i’m scared but don’t know if that is a good enough reason. please give thoughts!!