im sick of my best friend but im still afraid of losing her

 i (17f) have been very close with my best friend since i started high school. (i was 14) for years i always thought highly of her and she was everything i wanted to be like. i loved spending time with her and she was perfect to me in every way. she was funny, social, intelligent etc.

 since the beginning of this semester i get annoyed by almost everything she does or says. i started realising all of her mistakes and wrong habits

  it's like i had a curtain in my eyes that kept me from seeing her the way she is for all those years. i want to let her go but i had lost my friends in the past and i'm very scared of loneliness.

 i usually dont want to spend time with her anymore but we still do because im afraid to lose her and i feel like i get replaced at instant when i dont spend time with people in my life for a while.

 we are also roommates and we sit together at school so i see her all the time. i have other friends but i dont feel very close to them.

 is it normal? does anyone else feel like this? is this a bpd thing? i havent been diagnosed with bpd because my parents dont believe in therapy but i've been thinking that i have it for a year now.