I'm in similar situation, received Feb 2017, same status. Medical was done/passed in July. Have you been asked for police check? As I have not... No updates since July
Sometimes they don't change the status of the background check until you get DM, I've been told. I have a friend who applied Inland on January 9th, he sent PCC and Schedule A upfront, medical was never requested, however it was "reviewed" and "passed" about a month ago and shortly after he received AIP. He hasn't received SA yet as far as I know and this week he received a letter saying that he will receive another letter to set a date for interview. (Note that he couldn't link his application, so he can only check ECAS and receive regular mail from CIC).
Regarding the fact that you haven't been asked for PCC, if you didn't submit it upfront, I recommend you contact an agent on the phone or send a webform regarding it, I recently read here about someone who had the same situation and the agent told them that their PCC and Sch A should have been submitted already and their application was "on hold" waiting for it. They are full of glitches sometimes...