Feeling Stuck in My Retail Job

I work in retail and I have a position where I'm in charge of Clearance Merchandise. I make sure all the sections are cleaned and shoppable, and whenever I have a file open I have to show up to make sure I put all the new clearance in and get rid of the old (been on the shelf too long or damaged). I want to be promoted to a better position where I have an area that I'll be in charge of. The problem I'm facing is I want to do it, but my fear is that I'm not gonna be great. At my work I'm trained everywhere (cashiering, sales floor, backroom, office, flow merchandise out). I feel that I do everything and I continue to feel like I'm stuck. I want to move forward and be better. My management knows I have anxiety, but I feel like that is what they see sometimes when they hear I want to move forward. I don't know what to do.