You probably float a lot. Learn how to peek and clear angles and how to move, those are the most important things noobs don't actually do well. Sometimes a bad player can actually aim pretty well, but the movement is really bad.
Also, your friends that always pick duelists maybe dragging you down, create another acount to play for fun with your friends, and use your main acount to play seriously for yourself, and take every game very seriously and always with a positive mindset for you and for your teamates, a negative mindset may tilt your team and make you lose, don't complain to them, just give information and pep talks.
With this tips you will improve 100%. I played with friends and was Platinum, started to focus of myself, started playign with people who reeally wanted to improve and people who wouldn't mock each other the whole game and got Immortal rank, created another acount to play with my friends.
Follow these tips and you will get better fast.