When I was a teen, a lot of us thought the end of the world was at hand. That was nearly half a century ago, so I encourage you to take heart, Green_Ali. Maybe the end result isn't this life but it's about using this period of time to prepare for what is ahead. Remember how boring and long school was, years and years of sitting at a desk, bored beyond measure, wondering what it was all about anyways? Well, at 18, you don't have to do that for much longer. What I noticed, for what it might be worth to you, is that all those years of preparation were so I could be a functional adult, but I seriously did not connect the classroom with the life ahead. (I admit we could do a better job than 12 years of mandatory boredom, but that's not my point here.) Had I really connected the classroom with real life, I'd probably be a wealthy retired orthodontist or something, spending my retirement with self-funded mission trips to help others function more effectively.
From what I read in the Bible, God has no intention of just saving a bunch of sinners. He wants to enjoy us, to relate with us, to have us relate with Him, to make of us our best individual selves. If I can explain how I see it, it's not like He sits up there viewing us as a video game where He can cause one person to win while wiping out another. It's more like the most caring love you can ever imagine wanting the very best of your life, wanting you to succeed in being the most effective and solid person of the highest integrity, actually holy (separated for God) in the way that He is holy (separated from all the common). And when I read both the old and new testaments, I get more than a few hints that this isn't about just not dying, it's about really living.
So I can tell you that my brain really began to open up and things began to make sense when I finally decided to step into a course. People had told me that the most important thing was to get moving, and that God could more easily direct me as a moving entity than He could if I just sat there trying to decide what was the ultimate perfect path. Quite honestly, I think they were on to something there, but for the most part I didn't actually start moving until many years later. Once I started a deliberate path, I went to college for a useful degree in a field I figured I could enjoy and offer a useful service to people and make enough money to have something to share and a skill I could use in retirement as a mission. Other people have other goals, but this one fit me and got me moving. And I did find that things seemed to make more sense once I got moving toward a goal. I found that over time my goal shifted from here and now to seeing more how God wants that relationship with us for ever, and this life, this half a century, has been preparation time for THAT eternity ahead. What a wake up call that has been!
A lot of it was getting grounded in the Bible and in my own responsibility to have action in the world - to DO not just to BE - to actively add good to the situation around me. I encourage you to make a habit of reading the Bible daily. Make and keep a plan to read it through at least every year. After putting your trust fully in the Lord Jesus Christ and the access to the fullness of God that Jesus secured for us, being washed in baptism, and following the kind of life that He is calling you into (hint: it will look a lot more practical than you might think, with things like treating people fairly, considering others as well as yourself, speaking the truth and not deceiving self or others) then just keep putting one foot in front of the other and you'll find that sense of solidness, no matter how much time is left.
We don't know how much time is left. Many people look at world conditions and think the end is near. The end can always be near, like our next breath, but it might not be quite yet. The Eternal and loving God will have to make an end of this current world system at the point of time when His own people aren't even safe on earth and the wicked people have had their last chance to change their directions. My ongoing prayer is that our nations will repent of their wickedness and that I will see and root out the wickedness in me. God created a beautiful world for us to live and thrive here, but as long as people have the God-given right to make decisions, many will make hateful and hurtful ones. According to the story, God has rescued His people from wickedness before and will do so again. Just make sure you define your life so that there's no question where your allegiance exists!
God allowed you to be here in this moment. From the 18 year old I used to be, my best suggestion to you is to start now and see what happens! I'm hoping the very best for you!