It's easy to see how your packets are leaving your network, but hard to see what happens to them after that. Differences in routing and preferential traffic shaping mean that your traffic may take a very different route coming back as going out.
One way to get more information about what's happening is with "looking glass" servers. These provide snapshots of routing at various points around on the Internet so you can see what the path to your network looks like from out there.
There are a bunch of them out there, with some lists here and here.