I think you're getting overly anxious about the confrontational part of things. Fact is, when refereeing teenagers, you are going to have confrontations. For some of them, it is a badge of honour to receive a booking or a sin bin. Even a sending off. It is only when they start to mature and realise the effect on their team that they start to change and that comes down to parenting, coaching and the right culture in that team/club. By you avoiding sinbins, you are also making it harder for the next referee who will almost certainly get grief for using the sinbin in the correct way.
I would suggest to try to change your mindset and don't look at it as a confrontation, it's just like every other law of the game that you are enforcing, you are are there to enforce them. The player chooses to show dissent, it isn't an accident. Unless they have certain neuro issues which means they can't control their emotions.
Remember also, the player does not get a fine for a sinbin but they do for the other bookings so sometimes you are doing them a favour by sinbinning them.
What would help you also perhaps, is doing some lines. When you see other referees using the sinbin and you then hear the conversations on the sidelines, the first thing yo uwill hear is the coach or parent saying, 'what did you say'. That will be followed by, 'well you should keep your mouth shut' Followed seconds later by,'how long left in the sinbin ref?' That will be repeated on the minute every minute until you allow them back on.
Finally, I would say at least half of the time maybe more, when the player comes back on, they do at some point apologise to the ref even when passing about their comments. That feels really good and helps you with control.
Stick with it, best of luck, it's good that you are seeking advice on here.