Hello

Hi, my name is Tiffany. 
I'm a 16 year old girl (17 in March). 
I don't have a job, I'm studying year 12 this year and have no clue what I want to do when I'm finished. My mum wants me to become a doctor because I said it once but I'm really not that smart I'm failing all my subjects and it makes me stress out when I think of school. 
My mum is always at work and my stepdad works 4 hours away from home and only comes home on the weekends. My dad lives in Queensland with his beautiful family and one day I wish to move there maybe. 
I have an ex boyfriend named Philip and he was the best, he was my first boyfriend, first kiss and we lost our virginity to each other, we were together for 8 months. We broke up about 2 months ago now and it hurts everyday. It's my fault I told him I didn't feel the spark anymore but I don't understand why I regret it so much. My entire family hates him because of how much pain he has caused me but in my head he is still my hero. 
Lately I've fallen into a rough patch and I don't know why. I'm always sad, I find it terribly hard to sleep I sleep for maybe 4 hours and I'm okay with it, it annoys me to eat but I know I have to because I don't want to allow myself to get sick. I think about death almost every day. My mum asked me the other day if I ever thought about dying or self harm and I replied with yes but I could never do that to you or the family and she simply laughed and offered me food. I'm not sure how I should feel about that but it's just always on my mind now. 
Everyday I lock myself in my room, I don't exactly have close friends to just chill with it's just like people I sit with at school so I'm not alone but we don't hang out after school it would be a little weird. I cry a lot and I'm not into anything I use to be. I use to love reading and going for long walks not knowing what he further held, I use to always have a smile on my face and make sure everyone around me had one too. Now it's like I'm in a never ending storm. I don't know why I've gotten like this. I don't know how to stop it. 
I don't know what's wrong with me or who to talk to and I don't know why I'm writing this or if I will even decide to post it because all of you people don't need to read this it's a bit of a waste of time I think I am a waste of time but I just don't know what to do next and I don't know why I'm like this. I don't know what I'm trying to archive or anything but I think I need help.