I can 100% relate. I’m 20, although with my babyface most people see me as about 15. As you can imagine, it’s not very popular with the ladies lol. I still haven’t had any real kind of success, but I can try and give you some advice I’ve picked up in my time and am trying to apply in my own life. Apologies if you’ve heard any of it before, a lot of it will probably be pretty basic and obvious but hey.

1. Focus on the way you look. This is one of those obvious ones, but it’s also very important. Attraction is largely subjective but there are traits generally viewed as more attractive by the masses. Get in good physical shape, develop a sense for style (/r/MaleFashionAdvice and /r/malehairadvice can be great even if you just copy what’s there, but ideally you can use them for motivation to eventually form your own unique sense of style), make sure you’re always smelling good, wash your face and brush your teeth regularly, all that jazz.
2. Try to not place such importance on finding a relationship and love. This is a real tough one, and something I’ve struggled with a lot. My life history has left me with a lot of insecurities about not feeling wanted, which manifests itself as a desperation for romance which is generally not very attractive. The couple times I’ve actually come close to finding someone this is what pushed them away - I wanted too much, too fast. There’s value in just slowing down and letting things happen as they happen. That said, if you have romantic intentions you should make them clear sooner than later, but it should sound more like “hey i like you and think you’re cute we should go out sometime” and less “you’re amazing and i need you in my life” if that makes sense. i know i fall into that trap a lot, i hear all these romantic songs and stories from my friends and just want to hop right into that, but theres a fine line between being romantic and smooth vs abrasive and desperate.
3. Lower your standards. this is a weird one for me to say, since like i said before i believe attraction is largely subjective. But going after less conventionally attractive girls will probably net you a lot more success. i can guarentee theres a lot of girls out there going through similar things to what you and I are, and they’re accordingly probably going to have “lower standards” too (i really hate this terminology but on a general scale there’s weight behind it). Compare that to going after the types of girls who constantly have men coming onto them... its just less competition for you. Of course if you’re just straight up not attracted to them then obviously that’s a no-go, but like everyone has their own beauty to them and being able to appreciate that in a wider variety of girls rather than just those whose beauty is already appreciated by most other guys.
4. Have patience, you’re only 18. I totally understand what its like, at that time it seems like literally everyone else is off dating and shit while you’re missing out.