Your 57 frames are smaller?? Interesting..
Mine has 55,7 TT, 18 cm HT (headset included) and 59 ST (center of BB to top of the tube, seatpost shim included).
As I already wrote above, there are days/pics when I think it looks funny... and sometimes it looks perfect
As you said, if it feels good, then it is good!
Damjan: your bike looks fine and is fine. But I do believe your frame is a 58cm, unless it is custom geometry. Colnago frame sizes are measured from the center of the BB to the top of the seat tube where it actually meets the bottom of the seat collar. So, a 58 frame would measure about 59 to the top of the seat collar (where you say you are measuring to). I suspect your headtube measures 165mm (between the headset cups). If it was a 57 it would measure closer to 158mm. Your top tube (c-c) is likely 563mm if measured accurately and the seat tube intersects the top tube (c-c) at 560mm to be precise. But at the end of the day, I think your bike looks very good and it seems to fit. I like the -17 stem on it and the bars you currently have. Looks like you can get plenty low enough with that setup if you want. And like Eurperg mentioned, the hoods are properly set lower than the tops of the bars with your classic bars. I really like this setup because it give you basically 3 progressively lower and more aggressive positions. Climbing on the tops of the bars, then lower and more stretched on the hoods then lower again in the drops. It pains me to see bikes set up with a rising stem, and the bars following that rising line, with the hoods continuing that line and ending up being the highest point for your hands. Think about it. As you get more aggressive and stretched out, you want to move lower and forward and maintain a comfortable position. If, as you move forward and more stretched and have to reach higher for the hoods, well... like I said... think about it. Of course, personal preference can and should override any guidelines others might give you, but it's good to weigh all your options and suggestions and come to your own conclusions.
Eurperg: Have always like your bike. And I concur about the Regale saddle needing to be pointed up a tad in order to be feeling like your not sliding forward all the time. I tried one when I first set up my C59 because I liked the looks of it but after a 100 miles I knew it wasn't for me. But same thing, I did have to have it pointed up just like you have. It was just too wide for me. But a really nice saddle.