Final pre-req courses

Over the last three weeks I've been working on registering for my last three pre-requisite classes for USD's PA program and getting more and more stressed.  There are so many schools now that offers courses online but I need to watch if they offer the correct number of credits.  They start mid-January and I wish I was in the middle of the courses.  Finishing my undergrad was tough but getting through these last science pre-reqs has been so much more difficult.  I just keep telling myself I've gone this far and survived, the rest should be fine.  Biochemistry, organic chemistry, and microbiology is all that stands between me and PA school at this moment.  I need to have them set up and ready to go before Jan 21. Otherwise I need to give my interview slot to another applicant.  These last courses must be done by June in order to qualify for acceptance.  I'm sure this stress is nothing compared to what PA school will be.