Congratulations on making it past 20 mg!! But that prescription needs to be refilled.
You are not quite out of the woods because at 5 mg and below it is especially tricky to try to go completely off pred.
If you just suddenly stopped the med, you could have a Crohn's flare or worse, a life threatening reaction to sudden steroid withdrawal.
Now is the time you need to be especially patient. If, after about 5 days of being on 10 mg pred, you can try dropping to 5 mg or to 7.5 mg.
It would be a shame to get this far in your taper, and then by rushing it, risk a serious set back and have to start all over again.