I think the main problem with dummies and why the ABA don't recommend them so early is that sometimes people use them as a substitute for breastfeeds because they think the baby isn't hungry. Sometimes newborns can need 8-12 feeds in 24 hours, so you feeding your bub every three hours is not over feeding at all. Sometimes my baby needs two hourly feeds! They have little tummies and breastmilk is much more easily digested than formula, so people offering advice based on what formula fed babies do really can be detrimental to someone just starting out with breastfeeding.
It sounds like you are really getting in tune with what your bub wants, sometimes it can take weeks to do that. Try a dummy if nothing else works, just be careful you are not 'replacing' a feed with it. For example, if your bub has a feed, then you could say that if he cries within two hours, try the dummy, after two hours do a feed. It is up to you, just remember spacing out feeds with a dummy can reduce your supply, so just keep an eye on the clock and if it has been a reasonable amount of time at least offer a feed first.
Good Luck