I don't know if you need a new bike, but you need to commute on a bike you love (or at least like), otherwise you'll start dreading it or just not do it anymore. For me both a pannier and an upright position are absolute nonos for commuting, not to mention rubbing brakes. I commute on a flat-bar mtb that is significantly heavier than my road bike, but it's efficient on climbs and I can get way down out of the wind.
I would bring the bike into the foyer, out of the elements, and lock the wheel to the frame. And preferably get on friendly terms with the guards.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett