I don't think it would matter. If you do runway, you will be wearing clothing, often times multiple layers of clothing so your shoulders would not be noticeable. Also, if you look at print like catalogs and magazines, most of the time, models are not standing straight head on. They are often times in a weird slouchy position or laying down, and what not. If you are hunched over how will anyone ever see the uneven shoulders. Don't dwell on your shoulders, you should be fine.