I moved to 4 hrly feeds at 4 ish months but still had a DF so we were doing 7-11-3-7-11 so still 5 feeds.
The main reason I moved to 4 hrly feeds was to fit in with the EASY. Mine are on the low end for sleep needs so were doing 2 hrs A and then the blessed 2 hr naps that I'd been trying to achieve since they were born, but was blessed with the 45 min nap monster with each of them till some magic at 4 mths, both times!
So we were on E 7am, S 9-11, E 11am, S 1-3, E 3pm, no sleep and feed 6,30pm asleep by 7pm. DF at 11pm and STTN from 10 and 14 weeks respectively.
Tracy's theory is that by 4 mths babies can take in more at each feed and can do longer A times as well but if your LO is still doing well on 3 hr feeds and with shorter A times (or perhaps shorter naps with the CN at the end of the day as well....) then I would stick with it for now.
Great that a EBF baby is STTN 12 hours....you don't hear of that very often ;-)
Just remember that when things start to get hairy it will probably mean that you'll have to increase A times and/or drop the CN and perhaps then move to 4 hrly or gradually with 3.5 hrly feeds over time...
for now, if its not broken I wouldn't be looking to fix it ;-)
HTH and good luck x
Siobhain.