It depends on a ton of other factors-- what clinical experience do you have? Have you shadowed or volunteered? Done any research? These aren't necessarily required to get into med school, but for a non-trad it certainly doesn't hurt. Also, how committed are you? I'm not questioning your intent, I simply need more information to properly give you a "what are my chances?" kind of evaluation.
Getting a PhD certainly isn't a bad route though. I was seriously considering it the past few years, especially since there are so many perks like paid tuition, laid-back grad student lifestyle, lots of free travel, working towards making new discoveries, etc. But if this just doesn't beat the thrill of medicine, then you should aim for med school.
If you're not ready for it this year, you have plenty of time to beef up your application for the future. It might be a few years but it'll be worth it.