I was like that when I was your age and ended up marrying someone when I was 19 because I wanted so badly to have a stable relationship I could rely on. To make a long story short, it ended in a bitter and ugly divorce. I was obsessed with finding "the one", but once I got older I realized I was just simply frustrated with being misunderstood by everyone that I thought finding "the one" would fix all of my loneliness issues. Unfortunately it doesn't, as you seem to be approaching that point now after so many failed relationships. Loneliness is the hardest part of being on the spectrum I think, but it's good that you realize you're young because the fact is that you're only just starting to dip your toes into the pool that is yourself and all your peers are doing the same. So if you're looking for a stable and serious relationship it probably isn't going to happen at this point
If I could go back in time I would tell my teenage self to put that "perfect person" in the future and concentrate on finding myself so that I can truly be that perfect someone back. I would tell myself that this quest for "the one" is just a response to my loneliness and frustration with being misunderstood all the time but unfortunately there is no "quick fix" to loneliness, and unless you're whole and completely comfortable with yourself to the point that you can stand on your own comfortable, that perfect relationship will never come. Now that's not to say you should step out of the dating scene. This time is the time to test the waters and learn how to swim. It's a little easier if you go into a relationship understanding that it's going to be a learning lesson and that it will end at some point in time, but just enjoy what you have at the moment and start to learn your likes, dislikes, and priorities. Relationships are THE most difficult and challenging thing for us on the spectrum, and there will ever really only be one successful relationship in your life, all the other hundreds of relationships will be heartbreaks.
I know it's FAR easier said than done, but look at each hurt as a lesson. Also remember that no one is "perfect", so that "perfect one" is going to be the one who is willing to work through the hurt you cause them and vice versa to come out the other end together. And that's where this time in your life is handy, to figure out what hurts you're able to weather and which ones are completely unacceptable and intolerable. Get out there, have fun, and don't be afraid to get hurt, because all of it is necessary for the learning process.
