What a sincere, kind person you must be to be having these feelings. In my opinion, the true difference between animals and people is their ability to express love. Have you ever had a pet? No matter what you say, do, or how you act your pet loves you unconditionally and always forgives, always. Most people are incapable for some reason to express unconditional love and overlook your short comings and the mistakes you make, which are of course only human.
You have a reason to exist - You really do. Try not to over analyize it. Try to only concentrate on the things you enjoy and in those things you will find your true purpose. Count on It!!!