Well with regards to your feeling weird when you were pregnant and the floor moving and other weird neurological things, my wife always had that, plus a feeling of of her arms being filled with air ( seriously) and disorientation and dizziness, as well as a host of other things- good thing is it was found to jujst be nothing (not that could ever say exactly WHY it was, just that it wasn't life threatening) and she's alive and well years and years later. With regards to your other symptoms, anyone at all COULD have cancer and be none the wiser until they become symptomatic, but from your post you are quite young and therefore not in a high risk bracket to start with and it could be a host of other things, but you have recently had a baby and are suffering from anxiety- and that is the key to your problem- you need to get a better handle on that so you can see things in perspective and not panic yourself silly over something you read on the internet.
Someone like Sqad will be better placed to advise you on your medical stuff, but as for your anxiety, go back to your Dr, tell them what you've told us and that you understand that your anxiety is a contrivutorty factor and need some further help with that, at least then you will be less terrified and better placed to rationalise everything, as anxiety disorders are truly terrible.