Tying in to existing hardwood flooring
Yes, you need to rip the starting board to match what's protruding into the bedroom. First establish an accurate straight line based on the existing flooring. You may need to taper the starter to fit an out-of-square or curved wall. 

Update: I didn't initially catch that you had ripped the final board in the doorway. That board should be removed and replaced with a full board.