Hi, J.. Well, when a newborn or even an older baby farts, it's normal for it to be loud because a baby doesn't try to hide the sound, since he or she doesn't have any embarassment about farting. So don't worry about the volume of the fart.
I suspect that your baby isn't getting a good, tight seal on the nipple when she nurses, and that's giving her extra gas. Make sure that when she's nursing, that the nipple goes straight into her mouth, and that if she turns her head, that the nipple continues to go straight in through her lips. You also should burp her every minute or so, more than you might think is necessary, in order to get the gas up so that it cannot accumuluate in her stomach.
It's possible that the formula, even thought it is supposed to be gentler, is causing the gas. If it's made from soy, it can do that. Soy causes gas in adults, as do many products made from vegetable sources. Try her on something that is free from soy, but possibly lactose-reduced. It's possible that she's allergic to soy itself.
My son is 29 years old, so I'm not up to date on all the modern bottle nipples, but I used the Nuk nipple on his reliefe bottles, and this helped eliminate not only gas from bottles, but also it gave him a better sucking experience. I don't know what else is available, but I was happy with Nuk nipples.
Also, make sure that both the water you use for the formula and the bottles and nipples are STERILE. I made the mistake of not using sterile things, and I had a week-long screaming colic fit to live through, not to mention how much it must have hurt my little boy.
I hope everything turns out alright, and your baby becomes comfortable with her formula.
Peace,
Syl
Also, try giving her water if you suspect that she's just nursing in order to suck.