I don't remember too much, but the main character was a girl living with either her mom or grandma or aunt. And she lives a pretty normal life except for not being let out much. One day when she's in her backyard garden she trips and fall and leaves a massive gash on her arm? I think. She bleeds a bit, but then blue liquid starts coming out. She is suspicious and sneaks into her guardian's room. After searching for a bit, she stumbled upon a computer with her code written on it. She finds out she's a robot and runs away.
I believe this is The Adoration of Jenna Fox by Mary E. Pearson. (2008) as per Short book involving a car crash and artificial humans
Who is Jenna Fox? Seventeen-year-old Jenna has been told that is her name. She has just awoken from a coma, they tell her, and she is still recovering from a terrible accident in which she was involved a year ago. But what happened before that? Jenna doesn't remember her life. Or does she? And are the memories really hers?
The blurb on the back of one of the editions:
Jenna Fox wakes from a year-long coma following a devastating accident, her memory a blank. One day she cant walk; the next she can. One day her right eyelid droops; the next it doesn't. Her parents call her recovery a miracle but at what cost has it come? What are they hiding from her? And why does her grandmother, Lily, hate her so? When the memories do come, they're more than anyone bargained for, and as Jenna struggles to work out who she is, and what exactly makes us who we are, one thing becomes very clear: Jenna Fox is no ordinary teenage girl.
She lives with her grandmother and mother, and indeed, a cut on her hand reveals the reality of the blue "Bio Gel" inside of her that preserves her organs.
I sit down because I don’t know what else to do. I look up at Claire. “What’s wrong with my hand?’ I lay it on the table and spread the gash apart with my fingers. The skin lies on a thick layer of blue. Blue gel. Beneath that is the silvery-white glimmer of synthetic bone and ligaments. Plastic? Metal composite? Mother looks away.
I'd previously provided this as the answer to Book about young girl who got injured and was remade in a robot body without her knowledge?, and was thus familiar with the work.