Due To A Rh IncompatibilityI Am O- And My Husband

Due to a rh incompatibilityI am o- and my husband is o + I took a combs indirect exam and results are positive this is my first pregnancy, and im worried if my baby will be ok the doctor is sending more test she wants me to take the combs test again and another test to see exactly what type of antibodies I have is this wasting time will my baby be okay im already 28 weeks pregnant and due in December. when should I get the rogram shot,.? Thankyou