This question can't be answered nowadays at least. What ever we do and discover are steps towards the analysis of reality and of course meaning of self and the reasons of existence of self as well.
Just live, be patient, feel, cry, understand.

We all have a purpose on earth what ever it may be... may be you just have not come across yours yet and therefor you don't know,, but some day in life you will accompish the goals that u were meant to. Then u will know

The best part in having a choice, we can define our purpose in life, and enjoy it.

I tell you what you need is "hope" and "positive thoughts"
Don't worry about why we were born, be realistic now-
Look at the big picture. Your life includes a lot of different things. Let go of the little things and be content. Be grateful for what you have and stop wishing for the things you don't have.
Gain inner peace, that's the way to go.
Peace.:)