You are not practicing sword. You practice something with bokken. I don't think you can learn how to cut correctly by practicing aikiken. Sign up to learn iaido (or some koryu ) with knowledgeable instructor, he will teach you how to cut.
You are not expecting to learn how to cut from advices by Internet, do you?
Szczepan is largely correct. But I am really quite suprised that he didn't also advise you to forget iaido as a means to anything other than drawing the sword out of the scabbard.
As Sugano Sensei once said when asked about aikido and sword "if you want mochi, go to the mochi maker."