Force feeding? Can you over feed a breastfed baby?

My LO comes off but then back on, sometimes I put her back on and she sucks for a few seconds, squirms then comes off. I keep doing this thinking it is my let down or she’s gassy. Then afterwards when I sit her up within 20 mins, she will be sick quite a bit. She also has reflux so I thought it was that but it doesn’t always happen so now I feel like maybe I’ve been accidentally force feeding her??