Ok,so here are some more thoughts on this.... You've already racked it to the bucket, yes it probably has more head space than a carboy so it's not optimal. However it's done. You've exposed it to O2 once in this transfer, the beer has probably revived fermentation some what or at least CO2 has broke out due to the racking. Most likely this breakout has displaced the O2 in the bucket by now. That's why I'm saying I'd leave it. Racking again now exposes your beer once again to a lot of O2, yes you'll end up with less head space and it'll probably be fine, but why do this? If you're going to rack it again you may as well bottle it or keg it at this point.
Cheers and good luck.
It'll be good beer, no worries