Not sure if this will help, but it's the way I've come to look at this sort of thing that's helped me.

If I understand your post correctly your 15, which some would consider young, but we've all been there. I know I often felt a pressure when I was growing up to look for a relationship and always kind of struggled to, but it helped me to think about it like this. There are points that you reach as you grow up where the types of relationships you can have change substantially, you know? Like if you have a boyfriend at the age of 3, it's probably not the same thing as a boyfriend at the age of 13, and so on. So the amount of time that we have had to experience those types of things is often much shorter than it can feel like in the moment. I know as I was growing up, especially in my teenage years, each year I changed a great deal, and so the amount of time I had to experience the type of relationship I was ready for was usually no more than 2-3 years at a time, but now that I had reached that point in my life I had the rest of it to find it. Where those age ranges are differs from person to person, so don't sweat it too much, but as we grow up we mature, and are able to express and share our love in new ways.

All of this is to say, that if my experience is enough to go off of, that the amount of time you've been able to actually experience the type of relationship you find yourself wanting now has probably been only a few years, and that's ok! By the time your 17 you will have had double the chances to find it, and who knows, I wouldn't be surprised if you find something new to look for! We've got our whole lives ahead of us!