Having struggled recently with making sure I got the right fit, I have learned a few things in the process. One is that the SO height does not matter THAT much. C-T size for your measurements, and more importantly, effective top tube length for your measurements, are the really important ones. What kind of bike is it? If a mountain bike, then you should definitely have some clearance, but for road bikes I hear a lot of people saying that it's not that big a deal. I bought a bike based on the SO clearance, then within a day of riding realized I was feeling cramped (I asked for advice here a lot), so exchanged it for the bigger size where the clearance is minimal but everything else feels better. How does it feel when you ride it? Does it feel natural when you get in riding position? Also, just lowering the seat is not something you should do just for the fit - you should decide that based on the distance to the pedals. Google the seat height heel-on-pedal method. Hope it helps, I'm kind of a newb myself so take this with a grain of salt.