Double edged sword on this one. How can you say you want to be a physician and then not have an idea what kind of physician you want to be? You really can't picture yourself in a kind of practice? Sorry, but when I was applying I day dreamed about being a doc all the time and I at least had some ideas about what I wanted to do in medicine. Now, that changed in my 3rd year of medical school when I got a better understanding of things, but I at least had an idea when I applied.
My favorite question to ask is, "Where do you see yourself in 10 years?" An applicant that can talk at all
intelligently about the type of practice they'd like to be in, the balance of clinic/hospital/OR/administrative/research time they desire, and maybe even the type of community (rural/urban) is someone who has a decent understanding of medical practice and of themselves. They actually learned something from shadowing and investigating the profession. If what they say sounds reasonable I know they've thought this decision through and aren't just going to medical school because it sounds cool. Double bonus if what you say is backed up with experiences documented in your application.
My point is you have life experiences that made you think medicine was for you. It's okay to leverage those in explaining your path to medicine.
The only caveat would be, don't paint yourself into a corner. While you might have ideas about the type of practice you see yourself in, you also recognize you have very limited experience and have an open mind to other specialties.
There's a lot of finesse that goes into a medical school application and interview. It's definitely not all about numbers.