Regrets, have I made a mistake.

I've been worried as of late that I have made a mistake by starting a career in accounting. I am 21 years old and at the time of leaving school accounting seemed to be something I would enjoy and be good at so I decided to study AAT instead of going to uni. I've worked at a small company for about a year and a half doing book keeping and general admin this was good start but wouldn't lead me anywhere, so I got a job at an mid-sized accounting firm and have been their since March, I thought this was somewhere I wanted to be but I am not happy and I have not learned anything since joining, I spend the day doing data entry or filing I know as a junior this is what happens but how long goes this last? I am studying level 4 and all I have every done is book keeping, I am starting to forget the things I learned in class as I don't use it at work. I've made my boss aware of how I feel, he assures me that it will be fine and he will get me doing other things but I can't trust him as it took 6 months for him to get me a desk and there are rumors of him leaving.

Have I got myself into a dead end job and messed up my foundation to build a good career ? Regardless I will finish my level 4 but do I then change careers as it seems the world of accounting isn't what I thought it will be. My mum tells me that everything will be ok and I am just trying to rush into things and I should give it some time but if I can't visualise a bright future for myself maybe there isn't one there for me.

Has anyone been in a similar situation or having doubts ? I have been thinking about this for a while and would appreciate some fresh perspectives on the matter.