It is normal for babies to regurgitate some milk after their feed especially while they are burping because the valve that connects to the stomach and the throat is not very well formed yet and is still growing. It will be ok on some days but not ok for some. That's what I experienced.
When your baby vomit, was it forceful? Is it smelly? My baby will vomit smelly milk that smells sourish. When I brought him to the doctor, doctor says he has mild reflux problem. Reflux is like heartburn in adults. Reflux is painful for babies and so they will kick a fuss when they are trying to burp. If the vomit is forceful, it could be a sign that something is wrong, but not always the case.
My baby also has problems burping and we can spend forever burping him. What we do is we change many positions so that he can burp. Babies below 6 mths do not know how to burp so we must help them to "force" the air out. We not only burp him by letting him sit upright, we also rest him on our chest and shoulders. Our pediatrician also prescribed colic drops, instead of gripewater, to help my baby burp better. What colic drops do is merge the small bubbles in baby's tummy into bigger ones so that it's easier to get rid off. You can get colic drops off the shelf but it's better to consult a doctor as the dosage for small babies is lesser than what is stated on the box.
Changes in baby's poo pattern, bloatedness, crying and discomfort are signs of constipation. She might be constipated by the FM. When you feel her tummy, does it feel hard? If it does, there's a lot of trapped air. You might want to bring your baby down to a doctor to get her checked especially if it is constipation. If babies are constipated for too long, they might get fever.