Here is my genuine, raw advice to the teenager in 2019.
Delete your finsta. You shouldn't have to post a black screen and a sad caption to get people to reach out to you. Real friends will reach out on their own. Stop worrying about being left on open or left on read. If someone really cares, they will reply. "Left on open for one minute" won't matter because you'll either know they're busy or they'll tell you they are but will get back to you later. Stop stressing over how many likes you get on a selfie on Instagram. You shouldn't have to delete something because it didn't get enough comments or likes. You should already know how beautiful you are- a person double tapping their screen shouldn't have to be your daily reminder and reassurance that you're a pretty girl... because you are a beautiful girl, and you should know that already without the necessity for constant reassurance of your physical attractiveness.
Who cares who watches your snap story? Who cares how many people swipe up on your selfie? The people that truly care about you will show it. They'll show up. In person. Not just via the internet. Social media can be fun; you get to connect so easily with people you don't see every single day. It's easy to become close friends with new people when you have a constant source of communication. But, don't let social media define you. "Likes" are just double taps of fingers across the world. "Comments" are things you should already know about yourself. It would be a lot nicer for us to start "commenting" on each other in person. Hey, you look gorgeous today. You're a beautiful person. Your outfit is stunning. Your eyes look so good today. These are everyday things we could be telling each other. Let's like each other in person.
Let's DM in person. Let's quit FaceTiming and meet up at a cute little coffee shop to vibe in person. Let's actually go somewhere and create memories that we can't over the phone. You're never really going to remember a deep conversation over text. Your memories won't be of face time calls and snap chats back and forth. The real memories are the ones we make at 3 am when our blood is pumping and we can hear each other's breathing and see each other's smile on our faces. The real Snapchat memories are the ones we are living in right now. We don't need Facebook to reminisce when we can make new memories with the time we use on the app. Social media is great- just don't let it become everything.