Hi!
I understand that you're feeling frustrated, but it's important to consider that there are so many great things in life other than sex and reproduction. You're not a failure, you're still young, and there's so many great things to see, learn, and do! There are even people who choose not to have sex, get into a romantic relationship, or have kids, and they're capable of living happy lives. Your purpose in life is whatever you want it to be.
There's over 8 billion people on this planet, and finding someone who loves you for you is just a matter of when, not if. For now, I'd think about why you feel the need to put yourself down this much. What makes you think that you have literally nothing in your life, and what would make you reconsider that thought? Do you really feel that you have nothing and you need to be in a relationship with someone to have something, or is it something that others have pressured you into believing?