Hey - I also worked in law before getting into med school. I would agree it's a bit of change going back to school after having worked for some time. And as you're a solo practitioner, you could definitely continue working (maybe part-time hours) while you're in medical school - that's something I wish I did during pre-clerkship at least. It keeps things interesting and can be a good source of income!
Perhaps you should consider applying, studying for the MCAT etc, and see how you feel about it during the process. The whole process will take at least a year - you could write the MCAT this summer and apply in the fall. It is possible you'll realize better whether it is something you want to do or not; however, no matter how much you've looked into the profession and how many others you talk to about it, in my opinion its hard to really know what being a medical student/physician is really like until you're there. For me, so far I do find the subject matter more interesting and I enjoy working with patients (a lot more than sitting in an office and drafting documents and reading caselaw), but the cost (both financially and personally) was higher than I originally imagined.