If you haven't set foot in a hospital in 3rd year, then something is wrong. I have heard of people in my school not being on resident teams in 3rd year (you almost have to actively try to make that happen though), but I've never heard of someone not being in a hospital at all. In all honestly, you should have complained to your school long ago.
I'm also not sure what "top osteopathic school" you attend (not even sure what that means honestly), but if this is the norm for your school, you need to out it and the rotation site selection process. No medical student should be in this situation, and applicants deserve to more what they're getting into. I'm sorry that your school has done such a disservice to you.
Stories like this are why we need improved standards for clinical rotations, and exemplifies just how variable experiences are across DO schools. I've said it many times, but I had surprisingly good rotation experiences. All cores were in hospitals and all but 2 were wards based with resident teams.
Every school (at least I believe) has good and bad rotation sites and unfortunately on many occasions its up to the students to make sure they get the education they want.
Now that all said, I still think it's what you put in and where you do your residency that has the biggest impact on you as a clinician. Across the board, med students even in MD schools are given such varying responsibilities and experiences as a student that you end up repeating anything important in the beginning of intern year anyway, so at best the learning curve is a bit steeper for those with subpar experiences.
For that 3rd year student, don't worry, 1-2 solid inpatient wards based aways would practically catch you up.