From my experience, from about 3-4mo, night wakings can become a bit of a "habit".
I did a 'dream feed' of sorts with my first ds, but never have with my second (also a Liam), because I am an early to bed, early to rise type person & so is my toddler.
I think because you introduced it after the 3/4am feed had become established it has become a habit for your lo, so effectively you need to break him of it.
If you ff, try reducing the amount by 30mls (1oz) every few days & then use the paci when you get down to about 30mls.
If you bf, it is a bit harder as you need to cut back on time, so let him suck until it is about 2-3mins, less than the "normal" feed time, then cut back by 2-3 mins every few days & once again use the paci.
On the other side, you could just cut out the DF, but if he is now waking for it, I think you'd have the same sort of problems.
Just make sure that as you cut back on the feed at night that you offer more in the day to make up for it.
HTH