17 going on 30?

Everyone is telling me to follow my heart, to go with what feels best. But what if my heart is torn? On one side I have my need to no longer be lonely. My need to be with someone, even if that someone is only second best. And on the other side I have the part of me that is so far past liking someone that it’s bordering on cliché. Only problem with that is I can’t have this person. So does that side of me really matter? Or is it void by circumstances?
I feel like I am 30 years old running out of time to make a family, not 17 looking for someone to spend time with. I don’t want a silly high school relationship. I want something that will last. That is the main reason that I have held out for so long on dating anyone. I saw people date for 3 weeks, and walk away like nothing happened. How did they even enjoy one another’s company if it was so superficial? I want someone who can care for me and who I can care about. I want someone to support me when I need it, and who will take my support when they feel the need. Is this abnormal for one as young as I am? Most people I know are jumping from boyfriend to boyfriend, never staying long enough to figure the other person out. Is that what I am supposed to be doing? If it is I think I may have a problem because I don’t think that I could do such a thing.