Re: Any other suggestions??
Prolactin levels are highest at night, so one feeding at night would be helpful. There are ways they can actually test how many calories your breastmilk has, I seriously doubt yours isn't high enough -- no offense, your doctor sounds lame. Why jump to formula without knowing for sure it's your milk? There is human milk fortifier that can be added in the case there aren't enough calories for the baby.
What have her weights been since birth and how many different scales has she been weighed on?
All those supplements, and even medication, aren't going to do anything if the milk isn't removed frequently enough, either by a baby or by a pump.
I would be asking a lot more questions before jumping to formula -- good for you to look for alternatives.