I'm a 17 year old girl. I hate human interaction and I want to be alone. I can't help it because that's my nature. Am I a bad Muslimah because I'm antisocial?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If you observe the obligatory actions of worship and abstain from what Allah has forbidden you, then you are in goodness, and you cannot be described as a bad Muslim just because you prefer isolation over socialization. However, a person should balance between solitude and socializing with Muslims, in good things such as attending religious lectures and Quran sessions and keep away from gatherings that involve nonsense talks and wasting of time, and of course gatherings that involve forbidden matters such as backbiting and gossiping.

Allah knows best.