Each baby is unique and different!
And I'm a huge supporter of breastmilk being best for baby. Is there a reason you want to supplement? To establish a good supply and breastfeeding relationship you should only offer breasts to baby. In fact it was essential to my breastfeeding relationship with my youngest to not have bottles or formula in the house whatsoever because I had a difficult time breastfeeding my first two and it was easy to turn to a bottle because it was there. Good luck!
I tried breastfeeding for both my boys and didn't last more than a month. I also had to supplement with formula while breast feeding. I used Carnation Good Start for both my boys. They say its the closest thing to breast milk. My boys seemed to transition well between the two and didn't turn away when the other was given.
My daughter hardly ever moved inside of me. Only one other person other than me could feel her. She is healthy 5 year old today. It is normal as all babies are different.
Don't know about Gerber w/ breastfeeding. I am not a breast feeder.