Formula Help FTM

My week old is a breast baby. He was loosing weight so his Dr put him on formula just for a bit so he could gain the weight (which he did). Now as a FTM I am just scared he is loosing weight again he looks smaller to me everyday (I stopped the formula because it was going straight through him). I think I will put him back on the formula I just have different kinds at home. Dr gave me Similac Pro Advance (small bottle pictured). But I have 3 others to choose from. Dr says they are all the same. Which one is close to the pro advance? Im thinking advance but wanted to go with pro total comfort since it ties into breast feeding. Sorry for the long post I just want my baby boy to be ok