I currently ride a Specialized lithia gel in a 155mm. I had the butt-o-meter fit and that's the size it said. I also feel like my sit bones are nicely supported. I have no girly bit squish problems, but there is something going on and I need help.

For 10-20mi rides I am super comfy. Longer 50-60mi rides and I experience chaffing on the inner thigh at the bikini line towards the back. I feel lit mostly when I am sitting in the normal position on on the saddle. When I scoot really far back on the saddle the chaffing stops, but then the pressure on where my legs meet my pelvis gets uncomfortable.

So does that mean I need a saddle that is more t-shaped? I'm not sure what saddles I should be looking at? Any suggestions?