Kaleb, if PT shows the signal going to the compressor at 0 VU and the compressor is only getting the signal down -3.5 VU, then you might need to increase the output level on your interface. Once the compressor input shows 0 VU, then lower the compressor output to 0 VU. At that point, if PT doesn't show 0 VU coming back from the compressor, then adjust the input level on the interface to bring PT back to 0 VU. Then everything is happy.
0 VU is a pseudo-maximum, and many record 3 or 6 db lower (depending on the track) to give them some headroom so your preferred recording level is probably fine. Are the -11.4 and -16 readings from a loudness meter?