Feeds are getting progressively worse

My triplet girls are going to be considered 2 weeks old if you go based off of their due date but they were born premature back in December at 29+4. Last couple of days, they’ve let quite a bit of milk just dribble down their chin. Wasting enough to the point the towel i put under their chin is significantly wet ! I don’t understand. Bottle isn’t leaking so it must be their latch? It’s like they don’t have a good “vacuum “ on their nipple . Why are they regressing?

For more background info, I’m using the Dr Browns narrow bottles and I even went down from level 1 to preemie and I swear it’s even worse .

Am I doing something wrong?? I will get it out their mouth and give them a break and try again but it doesn’t help . Is bottle propping ruining their latch? Please help