Hi Loop,
I had a similar issue with one of my girls and the change to the aptamil hungry at about 10 weeks, it did give us a bit more time between feeds and seem to satisfy her for longer. It gave the other constipation though so we had to keep her on normal milk!
As for the teats, I was quite confused about that one myself and bought all sizes in preparation. Sometimes babies can get bored feeding if they have to work harder for their milk - so the single hole teats may be too slow. The size two teats are faster flowing due to the two holes and suitable for older babies - likewise with size 3. Mine still struggle with the 3 holed teats as they are too fast for them even at 8 months! I've spoken to a lot of mums who have only ever had size one teats whose babies have been fine so I guess it depends on how well bubs is feeding.
I can't really advise on dream feds as my two didn't have them consistently - we adopted the trial and error approach