Hey 18 is not late at all! A lot of my friends and coworkers started making games much later than that. If you find that you're struggling to finish everything though don't forget itch.io has a lot of asset packs available for you to use: https://itch.io/game-assets
Making your first game can be very difficult, but be sure to celebrate the small victories and know that everything you make will make it much easier to make games in the future. Wishing you the best of luck!