Becoming a Physician's Assistant (PA) or Nurse Practitioner (NP) might actually be a really good fit for you. In both fields, you are able to specialize in a specific area of medicine, just as you would if you were a physician. They are very similar jobs, the biggest difference is that PAs must practice under the supervision of a physician while NPs may practice independently. The training is much less expensive and time consuming than what is required to become a doctor, and both pay an about 15k-20k more than the average salary for PTs.
To become a PA, you don't need to go to nursing school, you just complete the required prerequisites at a university. Though this technically only takes about three years, almost all PA school applicants have bachelors degrees, so you pretty much need one to be competitive. As long as you have the prereqs you may major in whatever you like, but most people choose traditional science majors like biology, chem, anatomy, etc. During or after college, you must gain hands-on medical experience. There are many different ways to do this, you can find a great list
here. Once you have built up a good application, you apply to PA school, which lasts 2-3 years depending on the program.
To become an NP, you must go through 4 years of nursing school, graduate and gain experience as a registered nurse (RN), then return to school for a NP masters degree. This program is normally 2 years long, but I think they can range from 2-4 years.
To put it simply:
Becoming a PA is 4 years of college + 2-3 years of PA school
Becoming a NP is 4 years of nursing school +
at least 2 years of experience as a RN + 2 years of NP program