Please Help Me I Don't Know What To Do About A Relationship?

Ok so im 16 & dont have a boyfriend. My last boyfriend was last year in january. Ive been talkin to boys since then but for some reason I cant find the right one for me. Im a very beautiful smart girl. Ive been heartbroken before & never wanna feel that way again. I dont really trust ppls. My little brother(12) & another person always tell me that im gonna grow up & be lonely. Hearing that really hurts me because tey dont know how I feel & how I felt. & I refuse to lower my standards for just anyone. I deserve the best. But I know I need to change myself as a person because the person that I am now hich is shallow wont allw me to be with someone. If someoneis not my type I cant give them a chance ive tried it didnt work. As of right now im not talking to any boys right no. Im trying to better myself as a person. My deepest fear is growing old by myself and not having a family of my own. Please help me. What should I do.?