As previously suggested, the graph standard is vertical 45dB-105dB and horizontal 15Hz-200Hz.
Turn off the smoothing, it's reserved for higher frequencies and not to be used with sub measures up to 200Hz.
Use a 75dB target and a subwoofer test signal from REW (not full range).
Anyway, your response is quite good. You won't likely hear the sharp cancellation at ~45Hz, so you can move the sub a bit or ignore it.
You have a bit of a peak at ~30Hz that could be equalized away and as such would allow you to turn up the wholesale level of the sub a bit to bring out the bottom end more.
Yeah, we usually recommend taking a sub only measure (with the mains disconnected) to get a feel for the equalization that it requires. The mains are then added after equalization to allow the adjustment of the sub phase control to smooth the crossover area.
brucek