Anxiety at work

Hi everyone! I'm new.

So I work as a community manager. It's pretty much customer service--I spend my days replying to people's comments and messages on social media.

Over the past 6 months give or take, I've started feeling super anxious about work. I second-guess every message I sent, terrified of making people angry and the situation worse. In turn, it takes me longer to get my work done, so I have to work longer hours, which of course makes me tired and more anxious.

I think, deep down there's a deep seated fear that I'm going to mess up and lose my job. But I have no reason to think I'll lose this job. I've been working with this company for years and so far have not had a single issue. I may not be super productive right now but I am doing other things well--I do complete my shifts on time and keep up with additional tasks as requested. My supervisor has not warned me once about this and she's been very supportive when I opened up about my mental health issues with her. So if I look at it rationally, although I can improve, I have no reason to be so afraid.

How would you work on stop worrying so much about people's reactions and the (so far) irrational fear of messing up so bad that you'd get fired? I've tried using Habitica to reward myself for every message I reply to, making the experience more positive. I meditate during breaks to lower my anxiety levels and I also try to just tell myself to stop overthinking my replies and just send them. These things have helped somwhat but the feeling of fear and dread is still there and it's not letting me be as efficient as I could be.

Any ideas would be greatly appreciated.