If I were you, I would meet with your professor and see if there is anyway for you to realistically get a B in the class. You mentioned above that you might get a C+, and I don't think that will do much except bring your GPA down even more, I would take a W instead. Second, I don't think it makes any sense for you to be studying for the DAT without being done with the pre-reqs for it. The more science you have, the stronger background you have before studying for the DAT, the better you will do on the DAT. I feel like you have a lot on your plate right now.
I don't think you will be able to get into dental school with a gpa of 2.9, what is your science gpa? You would be wasting money applying for dental school if you don't have competitive stats. I would postpone the DAT to august, take the summer to study while working jobs. Apply for a masters program to bring up the GPA and apply for dental school the year after. Again this is what I would do! Good luck and don't give up if you are really passionate about dentistry.