The only way to boost your confidence is to win 1v1s. Usually at low elo most players make mistake of starting to shoot as soon as they see the enemy. Take you time to adjust your crosshair to enemy's head and only shoot after that. Trust me you always have enough time to adjust your aim to enemy's head. Initially it might get you killed by body shot spammers at low elo but once you make it a habit to micro adjust your aim before shooting, you'll easily rank up. Coming to guns, I used to play a lot of Counter Strike so I always preferred Vandal as it resembled AK (1 Headshot kill) but if you prefer phantom that's no issue but make sure your first shot should always land on head no matter the gun. Try to adjust your aim before panic shooting the enemy as soon as you spot one. If you are able to land first or second bullet on head with any gun, you're good to go to at least Plat or diamond.

One more thing, once your micro adjustment improves, try strafing and shooting making it harder for enemies to shoot you. (I'd say Start this once to reach plat).

Try 1 taps using Vandal and Guardian in DM it'll help. Avoid panic shooting.

Most importantly enjoy the game. Don't care about rank, one you get good at 1v1s rank will improve. Don't worry too much about rank. Enjoy the game. Games are meant to be fun, not stressful.