Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Washing impurities after relieving oneself whether by using water, or stones or tissues or the like is an obligation. However, it is better to use water after using any material that removes the impurity. The purity is obtained by washing the impurity away, i.e. removing the stickiness from body.
It is narrated in al-Muhazzab that if one wants to suffice without using water he has to do two matters:
First, removing the substance of impurity till the place becomes free from impurity. However, the stains that remain and could not be removed except using water do no harm. Second, wiping the place three times.
Cleaning only the external place of impurity is compulsory in Shariah. Therefore, one should not bother himself by inserting something inside his body, and if one observes impurity by doing so it does no harm since cleaning the external place only is sufficient.
Finally, through the afore mentioned details you may know that what you are practicing is not correct, Shariah does not order you to do so, rather you are putting yourself in troubles and hardship which is not allowed in Shariah. Allah Says (interpretation of meaning): {….has not laid upon you in religion any hardship,….}[22:78].
Know that Islam is a very comfortable and easy religion.
Allah knows best.