You don't need to have underlying issues to see a psychologist. I think you desperately need to talk to an unbiased third party about what you have experienced in life, and they can help you work past it and move on.
God would not have put you on this earth if there were no purpose. Suicide never is the answer. Absolutely never. He has a purpose for each and every person.
Perhaps it may help to read about some of the saints who suffered a lot, yet still were close to God and persisted through it. Look, for instance, for the writings of St. Faustina.
There are many evil things in this world, and it looks like you've seen your fair share of them. However there are many good things as well. I think that it'd be a great comfort to you if you turned to God for the grace to get through it.
I'm sorry if you are not religious, or don't believe in God as I am speaking of him, but he is the source of all good things, and will bless you if you turn to him.
Please don't make any rash decisions. Remember the choice is final, and there's no turning back once it is done. You only get one life to live,. Trust me your life is not devoid of purpose; you just haven't found it yet.