I am 17 years old and for some unknown reason I can't stop crying.

Since the age of 14 I have been to and from home in which I had a violent relationship with my mum and felt totally estranged from the family... She kicked me out on my 16th birthday and I have been living independently ever since; I started in 2 hostels, then a shared house and now a flat, I am living on benefits and am barely affording to survive as I have no help emotionally and financially. I completed school with 8 GCSE's, all A-C grade and also completed a Business Administration Apprenticeship, yet my mum and dad still see me as a 'failure'.

I come out of an awful 2 year relationship where I was cheated on, lied to constantly and which also sometimes resulted in fights, I also had a miscarriage at 15. I am still extremely close to my ex-boyfriends mum; she does everything for me and has always been there for me since day one, I look at her as a mother figure and would be devastated if I lost her, she is also like a best friend and I tell her everything...

Lately I cannot stop crying and I don't know why, all I have to do is drop something on the floor and I'm in floods of tears. I have no confidence, no motivation, I feel tired all the time and constantly am snapping at people for no reason.

Any ideas as to what's wrong with me ? :(

I am so sorry to hear about your situation. You have been through a lot so it doesn't surprise me - what your saying. You have a lot to handle and you are doing so at such a young age. It sounds like your parents never made you feel good about yourself and that's why you struggle.
You might want to find a therapist (some are even free through the city) and have someone to talk too. I think you might have (although I am not a doctor) a mental illness called ;Borderline Personality Disorder' which is the medical term for not being able to control your emotions to the point where you can emotionally bleed to death. See if you can find some free or low-cost counseling to help you with what you are dealing with. I have Borderline Personality Disorder and have had it for years. You need someone to help you get over the pain in your past.

To back this statement up, I saw a therapist for 2 years and it helped TONS. This was someone that listened and gave unbiased responses... lol, sometimes even explaining what I just said back to me.. and then I heard how ridiculous my thought was.. kind of funny.

You seem to have had some rough things in your life that would give perfect reason to be crying, whether you know it or not. It will get better, hang in there.