Congratulations on 3 weeks!! I had similar feelings when I began recovery. I promised myself that I would put everything I had into recovery for 6 months. At the end of that time, if I felt the need to pick back up, then I would.
I don't think I even got to the 6 month mark when I realized I had NO desire to go back. I do think, however, at one month I was still thinking "okay, just 5 more months and I can pick up", so it wasn't an instant thing.
Hugs and prayers,
Amy