It is a Bid’ah as it is not part of the Salah! However, you should work harder on concentrating!

When I do salah, I always forget how much rakah I did, have I already done sujood or not, and other problem about memory too. I found a way to overcome this problem, example when I do first raka’ah in salah I quickly look something,example pencil, so when I got confusion I can remember the pencil and so I know I am in first rakah. Is this is bid’ah?