Re: I need some advice/opinions.
I'm sorry that you have had such a hard time. It's actually pretty normal for infants to cluster feed in the evenings, and doesn't mean that you have low supply.
It's unrealistic to think you'll get to a point of pumping out 16 ounces - that's a ridiculous amount and generally only happens at the beginning because your body isn't sure how many babies to pump for.
I think you can at least reduce the amount of formula supplements, but you should contact an LC again, rent a hospital pump and PUMP, PUMP, PUMP. And nurse more often too, and follow the nursing with the supplement.
Here are some links that might help you:
Lilah 10/08 nursed 25 months
Beatrix 01/11 nursed 30 months