I agree that the pacifier needs to go.  

 I would argue with  your statement that "baby is attached well, but..."  Attached well, to my mind, means that the tongue stays continuously under the areaola, rhythmically pressing against it and releasing the pressure, but never changing the latch.   With tongue thrusting the infant is persistently breaking and reestablishing the latch, with each thrust pushing the nipple away and pulling it back with each swallow.


Two things that I do with infants that are persistent at tongue-thrusting.

1) Suck training.  I don't know what this "officially" means.  But I have them suck on my finger so I can assess what they are actually doing, and also see if during the sucking, they convert to the right movements or not.
I then have the parents feel the same things, then demonstrate to them, sucking on their fingers, what is happening, as opposed to what should be happening.  Then I have moms, or other family members, let the baby suck on their fingers just as a feeding is about to start, and switch only when the actual "latching" behavior occurs.  Sometimes they have to take the baby away from the breast several times, and back to the finger to reestablish the suckling behavior.

This is what I do, BTW, also with babies who persistently are gripping with their gums, or curling their tongues on the roof of their mouths, as both these things can lead to a tongue thrust as well, as the infant seeks to adjust to a proper latch.

This is one of the places I find a nipple shield helpful.  Since it gets the nipple and pressure on top and to the back of the baby's mouth, it bypasses some of the incorrect "sucking" and encourages "suckling."


2)  I do a lot of postural things with babies that encourage a dropped jaw, which seems to help break the pattern of thrusting.  It is very hard, for instance, to have a dropped jaw and a tongue on the roof of the mouth.  

Massage at the TMJ for the baby who is not opening his mouth very wide, therefore all tongue movements are essentially tongue thrusts. 
 Massaging back of baby's neck, and moving neck and head gently through figure eights, while 
 I do a semi-traction thing of the spine, which I don't quite know how to describe (a video here would be worth 10,000 words).  Basically, I stabilize baby against my hip and flat along my forearm, his head in my hand.  I lower my arm to put the baby at a downward angle, letting his own body weight stretch his spine from hips through neck.  I have his head supported by a wedge hold at the back of the neck.  You can feel baby's body elongating.  And sometimes feel the spine and neck uncurling.  I don't get the baby completely upside down, but about 30 degrees from it.    It's kind of like those hanging-upside down-thingies for adults, but with support.  (I've been doing this for years, but recently attended a lecture by a chiro for infants, who does the same thing in adjusting the babies who come to her)

Feeding in more sitting-up type positions, or alternatively with baby face down on mom's breast.  Sometimes putting them for just a feeding  or two in the "postural" hold, disorients them enough that they forget that bad habit of tongue thrusting while trying to figure out this new position, and when you go back to cradle hold or others, the problem is gone.

Hope you can find something in here you weren't already doing.

Sincerely,  Chanita, San Francisco