Baby crying and fussy

My baby is 5weeks and 3days old, she is having mixed feeding (bottle for formula and expressed breast milk as well as direct latching). Sometimes after bottle feeding baby still crying and seems to want more (I’m feeding her 4oz). Because she took 4oz of formula milk, I dare not give her direct latching. However she will cry and become fussy unable to nap until I direct latch her. I’m not too sure if anyone having same problem?