Possible reflux?? Over eating??

So my daughter is 6.5 weeks old. I tried breast feeding in the beginning and she projectile vomited after most bottle/nursing session. I was barely making 2 ounces a pump so when she started eating more I gave up on breastfeeding because I was already formula supplementing. I tried Stomach sensitive and she began vomiting more so we switched to Soy and the vomiting pretty much stopped. She still needs gas drops daily and a ounce or 2 of prune juice a day (dr recommended) to keep her from being constipated. But about once a week she has a day where she vomits multiple bottles she eats and will vomit and then want more instantly because she just projectiles her whole bottle! We burp her after each ounce. I don’t know what to do. I’m not sure if she’s over eating trying to comfort or what! She chokes a lot while eating even with newborn nipples on our Avent Natural bottles. She refuses a pacifier because I thought it would help and keep her from over eating. I’ve tried Nuk, MAM, Avent Soothie and she spits them all and if I try to force it she gags!!! Anyone have any idea on a paci she might take?? Does anyone have any suggestions as to why she only vomits on random days now all day. My husband and I both have sensitive stomachs too