OP...as I could tell my your description bike size, your fit is quite a ways off. As I stated earlier, you are on the right size bike.
I am not one to recommend a professional fit, but you need one. You are basically riding the bike like a beach cruiser.
1. bad posture aka hunch back...limits neck flexion and lengthens reach to the bars because a curved back is a shorter back. Proper posture elongates the back and decreases reach to the bars and hence you need more reach.
As a subtext, those that feel more comfort upright feel that way because they generally ride too far forward relative to the crank center. Moving weight rearward takes pressure off the hands and unweights the torso allowing it to lean forward more comfortably.
2. 20-30mm too short a stem and you need 10mm more setback...perhaps a bit more setback. Stock single bolt Spesh posts are 21mm of setback. I like about 28mm or so and my leg length is close to yours.

In summary you want to move your saddle back, rotate your pelvis forward and balance your weight fore/aft on the saddle with the rear part of the saddle 'level'...which means nose up.
Once achieved, your hands will have less weight on them, you can stretch them out a bit and ride more comfortably and elongated on the bike....much more aero and be able to lay down a lot more power.

Roubaixs are fantastic bikes and I love mine but your fit is quite a ways off even for the 'average' guy. A racers fit will be even more aggressive.