Marta asked me to stop by!
There could be a number of reasons for feed size dropping, common ones are needing to switch to a faster teat or needing to increase the time between feeds. Both my formula fed babies were at 4 hours between feeds by 12 weeks, they couldn't do 2 hours A time for a proper EASY but we fed at 4 hours and had a mixed up EASY until they could do 2 hours. If the teat is to slow they eat just enough but don't take a full feed because it's hard work, a faster teat means they can eat quicker and take more.
Does your LO actively look for food at 3 hours? I would try leaving a 3.5 hour gap and see if that makes a difference for a few days, or just try 4 hours if she isn't actively demanding food.

It's very common for formula fed babies to need longer between bottles as formula takes much longer to digest than breast milk.
Neither of my two had a dream feed, they either wouldn't feed in their sleep or they woke more often after it. I tried for a week or so then stopped it and just let them wake when they were hungry. They were waking around midnight and then that stretched out to 2/3am which suited me better

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Reflux is also a possibility - have a look at this link, it has a list of symptoms so see what you think.
https://babywhispererforums.com/index.php?topic=654.0HTH!!
Laura