Ustādh, i am a person who often forgets what rakah im on, i do a certain separation of the fingers of my hand so that i know what rakah im on and dont have to think about it, is that okay?

Ustadh AbdulAziz al-Haqqan

It is allowed. Shaykh Ibn Baz raḥimahullāh said there is no harm in folding a finger or two so as not to forget, because it is a small movement for the benefit of the prayer.