I used sub for a month under a doctor's supervision. I was on 2mg strips and cut them in half skipping days and weaning down to .25 before going off. I had tapered down to just 60mg of Norco from Oxy though. It was pretty rough and I should have jumped sooner like you did. I couldn't get lower than 60-75mgs without relapsing or using more. I was just using enough to make myself not sick.
Subs can last 36 hours in your system so that's why you are feeling okay. You might want to seek out an addiction doctor or therapist to help your sobriety. Just a thought.