I’m terrible with advice let me just get that disclaimer out of the way and I am merely speaking from experience. I’ve been a stutterer since birth and something that I have learned in my experience is that a stutter can be like quicksand in many ways, the more you fight it and try to will yourself not to stutter the worse and worse it will get, the more you try to hide your stutter it will very soon be overwhelming. I don’t know much but the one thing I do know for me is that the sheer volume of times that I have been bullied, made fun of by all sorts of people, (at my retail/customer service job too) and the way some people have made me hate myself. I came to a realization a few years ago and I will share what my experience was and I hope it helps! A few years ago I got so tired of trying to not stutter in front of people because I knew they would make fun of me or I felt like I was wasting their time, the realization I had was as follows: “Ya know what, Fuck. Them.” I had a realization that my stutter is apart of me and that’s just how it is, if someone wants to make fun of me or laugh whatever, I just know that the person will never matter in my life again going forward I will acknowledge that person but I will never give another thought to any thing they put forth. Real friends and co workers will like you for you no exceptions and if they can’t deal because of your stutter and say something like, “It’s not personal.” I take that very personal and I will make what I think vocal to their face. I say that to say this: After I had that moment where I had a very fast realization that I wasn’t going to take any shit from anyone I immediately noticed my stutter getting better, because I knew that if anyone brought it up in a tasteless way I will be the first person to tear them apart, I just mean for me it is very much a mental thing, if I think about my stutter throughout the day I stutter more because I’m conscious of it, however, if I acknowledge my stutter and just accept that it is apart of me it gets so much better. Now of course you’re gonna have good days and bad days I’m not saying that this mind set made my stutter go away but it helped me a great deal and I haven’t been nervous to speak on the phone or in a drive through near as much as before. I hope my experience has helped in some way OP, don’t let anyone give you shit for something that is apart of you, you own it and confidence is very soon to follow good luck! TL;DR: Fuck people who treat you differently because of your stutter. Your stutter is apart of you and you have to love yourself before confidence can fill your chest! Good luck out there guys stay safe!