You do not straddle a saddle, you perch on it. Its width is less relevant than you realize. On a 29'er you are sitting fairly erect, or should be. Your saddle at the proper height will have your thighs needing less clearance than one that is too high. You will need to be closer to the bars, not further from them. Bring the seat forward. Slam it. Forward. I am the same height as you. Same sit bone measure too (but its irrelevant) I usually have 29.5" from the center of the BB to the top of the saddle with the ruler following the line of the frame and seattube. What do you have? I like a saddle that is cut out in the middle, not just a groove, a real cut-out. Are any of your choices made that way? That's how you relieve pressure on prostates. I'd ditch the OEM seat and get something from Specialized or Terry if it were my bike. Put it on another bike. You do have other bikes right? Just kidding... sort of. What about tilt? Are you nose up, down or level? It matters, and what you think is your saddle "pushing' you forward might simply be you sliding forward on a saddle that doesn''t have enough 'nose up' to keep you in place. FWIW.