Hi, My Daughter Is 6 Weeks Old. Unfortunately We Happened

Hi, my daughter is 6 weeks old. Unfortunately we happened to put her on nanpro formula from day 3 along with breast milk. Lately after 30 ml formula she starts crying as though she doesn't want, but she still seems to be hungry. So we burp her & feed another 30/ml. She still cries after that. She has been wetting more than 10 nappies & has been gaining weight. So doc suggested she has silent reflux issues (as she doesnt vomit) and has suggested similac isomyl along with domestol. But she seems to get constipated with soya milk & am really hesitant to give her soya formula. Her stool movement with nan pro... Pls suggest which formula to go in for and also should I continue domestol