I agree with dylansmom. Sounds like the bubs moving around in there - but you may also be experiencing Braxton Hicks contractions. I'm not sure when these start, and not everyone gets them, but they are nothing to worry about as they are mock contrations and your body's way of practicing for the real thing. The only problem is sometimes they can be quite uncomfortable. As for being bigger above and not below, this is probably just the way you carry, in that it's just where your baby sits within you. When you are a bit further along you may feel the baby drop down a little and your bump will move slightly further down also.

Sounds to me like your baby is moving around. When your belly is hard or soft, its probably just the different body parts of the baby your feeling.. Mine was that way too. My husband used to say you could bounce a quarter off it. It'll get worse too as you grow. You'll feel elbows or a leg under your ribs which is painful but they will eventually move. Sometimes you can push pm the baby a bit  and make them move when it's painful. My little guy was constantly kicking me all day and practically until bedtime.