Advice - Motion Detector vs Contact Sensors

Hello. I recently moved into a new house, where the living room has 5 windows. Rather than buying 5 additional Contact Sensors, I opted to place a Motion Detector in the corner of the room, about 8 feet off the ground. There are, however, a couple of issues with this: 1. If I have the motion detector set to trigger alarm when in "Home" mode, it will also go off if I go downstairs for any reason (the stairwell is visible to the motion detector). 2. If I don't monitor the motion detector in "Home" mode, if someone breaks in through the windows in that room, it won't trigger the alarm. I'm stuck and don't really know what options I have, other than just buying a bunch of contact sensors. Even so, that then begs the question as to what usefulness the motion detectors actually have. The only other option I considered was moving the motion detector to a position directly opposite where it is (i.e., facing the windows while having its "back" to the stairwell, kitchen, and family room). Is there anything I'm missing or not considering here? Thank you in advance.