Are we over feeding my daughter?

My daughter is 3 weeks old exactly. She currently weighs 4kg from her birth weight of 2.89 kg. We feed her a mix of BM (~300ml, 80-90 per feeding) and FM (~600ml, 80-90ml per feeding) Some details: 1) My confinement nanny is taking care of her feedings. 2) she will feed her whenever she cries , to a frequency of 2h to 2-5h per feeding for formula milk. For BM, is can be as fast as 1h-1.5h after her last BM feeds. 3) we are giving her Enfamil A+ for her FM In total, we are feeding her up to 900ml of BM + FM per day. I am worried that we are overfeeding her and have voice our concern to our nanny. But she appears to be nonchalant about it. Are we too overly anxious about this? Is this normal?