Hi Susan,
Right now, there is no way to change the fact that those navigation-bar links point to Commons-related elements (so, “Blogs” shows only blogs on the Commons). In the future, we will be working to create Profile pages that are more modular and customizable, but we’re not there yet.
The only workaround I can think of is that you could conceivably set up a placeholder blog on the Commons so that it will show up nav-bar list of blogs, and then put up a link there that points visitors to your wp.com blog.
Eventually, if you decide to move your wp.com blog to the Commons (or vice versa), it’s very easy to export/import WordPress sites from one installation to another. One advantage of having your blog run on the Commons is that you’ll have a far greater selection of themes and plugins available to you.
At any rate, I hope that this helps; sorry that an immediate solution is not available.