The way I made my decision was by talking to a PT and hearing what he had to say about the field. I later worked as PT aide for him and with that immersion knew that it was the right field for me. My advice for you would be to try to shadow a few PT’s so you can see what they do, and talk to them about it.
Also, in terms of not being a medical doctor, I have a few thoughts. I’ve never heard a PT who didn’t love their job, whereas many MD’s I speak with seemed burned out. They make more money, but they also spend more time in school and training, and not a lot of time with patients. One of the things I love most about being a PT is getting to know my patients!