Sleep Regression, or??

Hey Everyone,

My reflux baby hasn't slept more than 4 hours overnight since she was two months old (4 months old next week). She went from doing four to five hour stretches, then three hour stretches, to now waking up every one to two hours for the last few nights. We will try to soothe her back to sleep without picking her up, which sometimes buys us another 10 mins and then she's up again. I always end up nursing her for what seems like another full feeding and she falls back asleep (she's EBF). She always seems restless (not screaming or anything) when she wakes up. Any ideas what is causing her to wake up when though she should be exhausted (not to mention sleeping longer by now)? Her reflux has thus far been well controlled with ranitidine, she has a well established night time routine, and I keep her upright 15-20 mins after each feeding. Is she just not getting enough feedings during the day maybe? Or is it reflux? This mama is tired and has to go to work in the morning, any advice is appreciated!