Wow, a doctor. Good for you. I'm scared of blood, so I basically knew I wouldn't make a good doctor. :D As for your question, I think we all go through that moment when you are excited about something and depending on the situation or experience, we lose a bit of it along the way. If you really want to see if you want to be a doctor, I would say maybe try volunteering at a hospital. This way you can see the day-to-day operations within a hospital. I'm not completely sure, but I think some hospitals have intern programs. You might want to look into that.
Another thing is, what motivates you to want to be a doctor? Do you want to save lives? Do you want to research new ways to fight cancer? Watch this video about why this person became a doctor: https://youtu.be/89aowrlN--k (Can't guarantee you won't bust a tear). Hope this helped. Good luck!
Dream big always, Vivian