There seems to be something about the 4 month age mark that throws babies for a loop. They are becoming more alert to the world around them, their bodies are growing so quickly. I suggest sticking with the 3 hr feeds for a bit longer. Also, if she is extra sleepy in the morning, don't try to have 2 hrs of A time, go ahead and put her down after 1.5 hrs if needed. If she's ready for her feed around 10:00/10:30, go ahead and give it to her. The 3-4 am night feed should drop soon, and she'll be back to eating a full first feed again. The other option is to limit how much you give her at 3 am to just enough to hold her over.
I haven't heard about dropping the df if the lo is waking for it. Rather, waking after going to bed is often a sign of overtiredness and inability to settle well enough into a deep sleep. Or, she's simply hungry.
Oh, just another note, my dd didn't do 2 hrs of A time until after she was 6 months old.