Medicine must be one of the great loves of your life. Just like finding a significant other, you don't ask to move in on the first date -- or even within the first month. Instead, you spend a long time getting to know them well, understanding their flaws and faults and realizing for yourself that they are greatly outweighed by their perfections. You have to build a good foundation in your relationship to survive any arguments or fights. You learn what to expect when you decide to live with them and eventually spend the rest of your life with them. Sometimes, some people get lucky, and are able to learn to love their significant others after jumping into a relationship. Most people aren't.
Well, medicine is one helluva mistress. It asks for more and more time and money, riding you raggèd and keeping you from sleep on your worst days. If you don't love it, it'll leave you broke, depressed, and feeling violated.
...Actually, it does that even for people who love it.
TL;DR. IHMO:
If you are doubting your passions at this point, it should be a resounding "no" to medicine. Education only gets significantly more difficult with less free time -- and therefore less time to remember why you began to pursue it in the first place. Remember the fire hose analogy: what at one time you were learning within one quarter/semester, you are now learning and tested on within two weeks. If you don't already have a strong passion, you'll find yourself wondering why you started when you're in the middle of the race and too late to turn back (at least, $200k too late).
Your mind can change later on as you have more experiences and "fall deeper in love" with medicine. Those experiences are what will keep you afloat and persevering through training.