At 9 days you should be past the worst and getting better each day (unless you were on methadone or buprenorphine , their wd is a longer more drawn out process). I have had some pretty bad habits and by day 9 the only real acute symptom was lack of sleep. I always found sleep (being able to sleep through the night ( at least 6-8 hours straight) took anywhere from 7-14 days or so
But really other than subs or methadone, usually the peak of the withdrawal is around day 3/day 4 and it slowly improves. Physically at least. You'll have some depression and blahness and fatigue and such still. But you're really in the home stretch now...
And truthfully, if you had a massive habit to the point you were having wd so many days later then codeine isn't going to do much but throw off your wd timetable.
Taking codeine now would be like awakening a sleeping dragon. Not a good idea. You may or may not reset physical wd, but you will certainly reset cravings and psychological wd. And really, you've come so far, keep going forward!