Interesting update! Based on all of your comments about your measurement, I told myself what the heck, I raised my seat to 72-3cm range and also raised my handle bar 1cm too. Guess what, I feel much more comfortable and I have more power!!. I could feel 2-3 MPH more speed along same stretch of the road!! that's 10% increase in power folks! anyways I think there is still some fine tuning to do but I suppose this will make many of you feel better about my frame size...
Well that's a great result - keep tuning the position and see what it's like for a while, as one ride gives a feeling but isn't descisive. As you get the position tuned in, try moving the saddle smaller amounts, say 2-3mm at a time and see how you feel. Personally I look for a saddle height which allows me to pedal smoothly from 70rpm to 115rpm or so, without sore feelings at the front or back of my knees and flat/ slightly pointing toes at the bottom of the pedal stroke. For setback I choose this so I can ride in the drops then take both hands off the bars (no bouncing up) and then hold my torso still or sit up without falling forwards. Then you choose a stem to put the bars where your hands are so that you can do 2x20 minutes in the drops without discomfort.
If holding the position in the drops is difficult, do the setback exercise (into drops, hands off bars, sit up slowly) 4-5x on each ride. This will activate your back and core muscles at the start of each ride, so they get used a bit more during the rest of the ride to help improve your stability. Off the bike, try the various plank floor exercises (put hands and feet on floor, then lift 1 hand or 1 hand and 1 foot, do in various positions so it's moderately difficult). Once these are easy try riding out of the saddle with one hand on the bars. Do the on-bike exercises gently at first as you can lose control if you get carried away.