You should be able to remove knee issues (assuming they are caused by bike and not running) on the frame you have as that is likely saddle height and position (fore/aft and angle) and foot position on pedal. However, the bars may then be 10cm too low and you will just move the problem to having bad back, bad neck etc,.
So very likely that a bike fit will indeed just tell you your frame is too small...
You should be able to remove knee issues (assuming they are caused by bike and not running) on the frame you have as that is likely saddle height and position (fore/aft and angle) and foot position on pedal. However, the bars may then be 10cm too low and you will just move the problem to having bad back, bad neck etc,.
So very likely that a bike fit will indeed just tell you your frame is too small...