I don't understand how the road bikers manage with all the holes, but they seem to manage them better then me, or I am very good at not missing them. Even the zig-zag no stopping lines feel like bumps to me.
Bear in mind that even leaving fit and position aside, not all road bikes are made equal and jarring feelings could be down to a great many variables.
Your carrera is a decent enough bike but there are some road frames that are famously comfy in your stated budget... Giant defy, cannondale synapse, felt z... Or I could state confidently the cannondale quick sl as very fast on roads but capable off road and preposterously comfortable.
Even tyres make a huge difference. Your weight, bike, wheels and riding style will have a bearing on what pressures to have your rear and front tyres. Post up these details and I'll offer a non professional opinion on what you could try. Sometimes under inflating tyres can make them even less comfortable than over inflating.
Finally, going away from drops isn't per se a solution for wrist and upper musculoskeletal problems. A bouncy hybrid that's too long will be just as problematic as a drop bar road bike, for example.
Finally finally, try before you buy, and get stretching and working out! Even a teeny bit of regular self-physio will make a big difference.