Can I use afrin in very low dosages every night for nasal stuffiness?

No. It is ok to use afrin (oxymetazoline) for 3-4 nights in a row and then stop. It can be addicting to the nose very quickly (by 7 days of daily usage) and then you get rebound stuffiness from the afrin (oxymetazoline). If you have chronic stuffiness you need an evaluation to look for allergies and other options to improve your symptoms.