I appreciate that this is a big deal for you, and many others around your age - it can feel like so many others around you have had, or are in, relationships, so you wonder when things will happen for you, naturally! Also appreciate that it's hard for you to talk about (well done for coming on here and discussing it, it's really brave!), but know that this is a safe space to talk about this
I personally think that you can be great in every way, but you need to let people know in some way that you're available and looking (not directly though haha!). It may be that people think you're not interested because you're quiet - not to say that being quiet is bad in any way (it's not!), but that perhaps others don't know that you're interested in them, or available? Either way, I think waiting and hoping for things to change isn't always a great idea, because nothing may happen and then you've let time just pass by, when you could be doing something about it.
One way that worked for one of my friends, is that if you get a friend you trust to introduce you a girl. It could be set up as a date, or perhaps you meet up as a larger group and spend a little time getting to them that way, and then develop from there. I know it sounds a little strange, but many people get married to someone they know, either as a friend, or through a friend etc. If you trust your friend to help you out (especially if they are more social and know girls etc), then that could be a way to go forward. I don't know if you are part of any social clubs (e.g. sports, faith), but that can be a good way to meet people too. Hope all goes well!x
Much love <3