Daughter with silent reflux ? Help ?

My daughter is 3 weeks and 5 days old . I’m breast and bottle feeding her . The formula we use is Similac sensitive for babies with lactose intolerance .

During feedings she’ll either eat without a peep , she’ll cry or grunt or fuss sometimes , or cry during the whole feeding . She also stretches her legs out , sticks her belly out (like arches her back) , and sometimes due to crying or fussing she’s slightly choke on the formula and then swallow it . She doesn’t really spit up after either . It’s rare .

I try to hold her up to eat and after I try to hold her up as well for a little while . However holding her up during feedings doesn’t help very much .

Am I right to believe she has silent reflux ? Is there anything else I can do to help her ?? It breaks my heart she has such a hard time eating ...