I struggled with my specialty decision up until the last possible minute (and actually a little bit past). Most people will know by the end of 3rd year what they want to do. The majority of the rest decide after the first 2 months of 4th year. Some people will have the same problem that I did, and end up choosing late. A small few will probably apply in 2 specialties.
It's OK to enjoy aspects of many different specialties. I certainly did. I loved emergency medicine, vascular surgery, ENT, Gyn Onc, general surgery, cardiology, radiology, trauma surgery, pediatric heme/onc, plastics, and critical care. I seriously considered several of these options, and was still debating my choice even as late as September of my 4th year. In the end, however, you have to realize that you really can't have it all. Overall, it's much better to have to pick one specialty from a list of many that you enjoyed, than to have to settle for the specialty that you "hated the least." At a minimum, you have this going for you.
It is most important to do a longer rotation (sub-internship) in the specialties in which you are most interested. This will give you a better idea of what your day-to-day life will be like. Still, even a sub-I is not much of an exposure, at least for making such a momentous decision. In the end, you have to go with your gut. You can only match in 1 residency in March next year.