Help! Baby is not drinking formula ?

I decided to supplement my breastmilk with formula. As per advised by my baby's pedia, we tried NAN HW.. I'm worried right now since my baby doesn't want to drink it from the bottle. It's been 2 days now. He's not getting enough breastmilk from me since I don't see enough urine from his diaper and it's color is yellow. I don't know what to do, I tried every strategy there is, still I don't succeed.