How effective is Lisinopril 2.5mg?

Hello been lowering my blood pressure and medication for the past half year and currently taking 5 mg of lisinopril. Been monitoring my blood pressure at home and have noticed that there is room to either lower the dosage to 2.5 mg or completely cut it off, readings have been in the low 100s and mid 60s. So the question is how effective is 2.5mg as I’ve read that at such low dosage it can be ineffective. Obviously I’ll be discussing this with my doctor but just wanted to see what others have experienced before.