How can you tell if you are a boy or a girl, or something else entirely?

Hm well based on personal experience I can say that it's up on the individual. Originally I identified as female, recently I took some time to do some actual healing and self care and over time discovered that I am non binary. So basically what I'm saying is you just need to take time and self care. It's a long journey full of ups and downs but if you're determined like I'm sure you are it will be fruitful. Please always remember that this adventure is different for everyone and it's okay if you feel like you figure something out and then it does not feel right anymore, that's okay and all part of the process of discovering yourself.