What is my point in existence?

So at the minute I'm seriously down, real down. I am a 17 year old female & right now I am at rock bottom. I tried my hardest at school to get the best grades possible & to be straight, they wasn't so great. I struggled to get into college, then 6 months into college I dropped out because I wasn't good enough for the course, even the tutors told me that, even though I put 100% effort into every session. (I studied Photography, but I no longer want to persue a career in Photography) Since I quit college, I have been searching for a job near enough every day. I have applied for countless amounts of jobs & not one has come back with an interview for me. I've applied for office jobs then jobs such as McDonalds & Dominos. At this rate, by the time I reach 18, I will be on Job Seekers Allowance & if that happens, I will be so upset, I don't ever want to be on Job Seekers. I just don't understand my point in existence. Even my 14 & a half month relationship with my boyfriend is on rocks at the minute. I can't ever see me making a change to this world & I know you're all gonna say 'Your family love you' etc etc. I just don't even know what to do anymore.