If you are serious about MD-PhD programs, I think you should consider spending an extra year doing research before applying. With your strong GPA and phenomenal MCAT, you have that much more to gain. Research experience is by far the most important criterion by which MD-PhD adcoms evaluate applicants. So, even with your scores, I think you will have difficulty applying with just 6+ months of research, especially if you don't have much experience designing experiments and writing-up/presenting results. MD-PhD programs put huge investments into each of their students; they want students who have shown a long-term commitment and enthusiasm toward research that will likely translate into a successful career in academic medicine.
In just one extra year of research, you can really distinguish yourself by taking ownership of a research project (or part of one) and trying to take it from beginning to end. MD-PhD adcoms love it when you design and perform your own experiments, create or modify experimental techniques, collaborate within and outside of your lab, learn from some failures, present posters at national conferences, write-up your findings formally and, if you are lucky, get published. These are the things that will make your application really stand out and allow you to shine in interviews.
Alternatively, if you want to apply this cycle, you might have much more success applying to MD-only programs (assuming you have good letters and some clinical experience). In fact, with your scores and your research, you might even be able to get into a top-tier school (but you better hurry, as the deadlines are FAST approaching). You can always do research as a MD, and some schools have in-house applications for MD-PhD if you want to apply later. Now, don't let me dissuade you from applying MD-PhD this cycle if you really want to (it's possible I'm grossly underestimating you from your brief above descriptions), but I do think your chances can improve dramatically if you deepen your research experience.
