Baby sleeps great.....until 4 am

So my 15 week old girl finally sleeps 6ish hour stretches when she goes down for the night. If she wakes up or stirs i will pick her up and feed her back to sleep and put her down. Around 3 or 4 every single damn night she squirms and grunts and calls out and when i breastfeed her back to sleep and put her down she does it again 5 min later. It’s like she’s done with sleep. I end up putting her in bed most nights at like 4 am just so we can get some extra sleep. Does anyone have the same experience? This constant waking every few minutes after 4 is what keeps me from transitioning her into her own room. Not trying to walk across the apartment 5 times in the middle of the night for no apparent reason