By strongly blowing your nose you might take the mucus inside the sinuses. In this case, because of bacteria, you may develop a secondary infection.
Neither mucus nor secretions, caused by cold, are the causes for stuffy nose, but the swelling and inflammation of the blood vessels in the nasal tract which were stimulated by the infection.
This is why it is recommendable to blow your nose slowly. Also, you may want to forget about the technique of cleansing the nostrils with hot water.
You can bring back your blood vessels in their original state by using drops or sprays which will also reduce the swelling and flow will be better.