I'm not sure what to do

I'm a minor, and i've been having off and on suicidal thoughts for about five years and I dont know what to do. I want to tell someone, someone that isn't related to me, and someone who won't look at me like I need to be locked up in a ward.

Usually in the summer time, my mental health drops. I no longer have school and friends to distract me with. I have no sports, and no major responsibilities to keep me from focusing on me. This has been routine, but I'm not sure why I feel like garbage.

I'm the eldest, which means everything gets placed onto me. It's "expected" of me to take care of everything, and parent the younger ones. I'm also stressed out about my mom, every little thing will set her off. I'm scared if I even play a song she doesn't like she'll flip out. I think she's bipolar, but I'm afraid to say anything. I get so stressed, my stomach hurts a lot and I feel myself getting sick. I guess that's my main reason for why I'm so suicidal. I feel like I wanna escape from everything? But I feel so selfish for trying to leave everything behind. My pet bunny, my little sister. My family. I don't understand my feelings, but I do at the same time.

I had gotten really close last night. I ate expired ibuprofen and benadryl, but coughed it up because I chickened out. I'm always sad, and tired, and I've been feeling nauseous no matter what I do. I guess the reason why I'm typing this out is to vent, but also for some advice.