Yup--no one can give you a precise number that will work, unless they're right there with you, at a fitting. The number is the one that works FOR YOU. Sure, some can point out some obviously wrong adjustments (if your hips are rocking badly, for example, or if your knees are way too bent at the bottom of the stroke), but the idea of a base number from the bottom bracket to the seat is an estimate at best--that doesn't even factor in your crank arm length. So raise the seat to where you are comfortable at--and knee pain trumps any other consideration at this point, IMO.