The fact that you have publications is not supposed to be an indication of your future career. (Primarily.) At this stage of your life, all it basically means is that you can do research, and you can do it well enough to get published.
Many MD/PhD students choose a certain course of research during their "in between" PhD years that has almost nothing to do with their clinical interest. For example, suppose after you finish 2 years of medical school you're really interested in biochemistry, metabolism, and diabetes. You then spend another 3-5 years writing your dissertation in this area. Then you go back to medical school, decide that internal medicine is not for you, and go for radiology. (And this happens quite a lot. There's nothing that helps you with your decisionmaking more than actually *doing* time on the wards.)
If this happense, the PhD isn't *useless*. The PhD portion of your training is as much about putting together a toolbox of methods (that you can use to apply elsewhere, if you decide to go in another direction) as it is about putting together an area of expertise.
The other thing arguing for the PhD portion of the MD/PhD being about putting together a toolbox is because by the time you finish your clinical training, you will be at least 5 years (2 medical school+3 residency) from picking up your research agenda again. That's a lot of time. Things change.
This is just a long winded way of saying that you don't need to worry that your publications are in different fields. They won't take it as a sign of wishy-washy-ness, but rather that you are capable enough to publish in a variety of disciplines. It's way too early for them to >expect< that much of a focus.
Cheers,
-a.