Sleeping Issues please help!!!

Hi ladies! My LO was born 10/25 so she is just over 2 months and I am having some major sleep issues.  When she was younger, she had reflux but seems to have outgrown it and the last few weeks she's been sleeping for about 6 hours through the night.  I'm almost exclusively pumping and giving her expressed breast milk all day minus one bottle of formula at night so I know she's getting enough to eat during the daytime.  The last few days, she is falling asleep and waking up every 20 minutes! When she wakes up, it's not even a loud "cry" but it's different and I tend to her for a minute and put her pacifier back in so she falls right asleep.  20 minutes later the same thing happens.  I know if she was hungry, she wouldn't just fall back asleep.  This cycle has been going on as I currently type this from 12am (it's now 2:40am). I can't keep hopping out of bed to put her binky back in her mouth every 20 minutes.... any advice or suggestions for what this is and what I can do to help her stay asleep?