Bless your heart. Your child chose your breast milk over bottle feeing. Are you not lucky!!!!! This is what most mothers pray for. Some mothers do not have enough breast milk to feed their infants.
Try consider your child and put her first before work for a couple of months. Four to six months is not bad atal. A mother's breast milk is the best milk,if nothing else, it fights infections.
Have you tried using breast pump to save your breast milk in a bottle? Do you know you form a special bond when you hold your child to breast feed her? If you do not do it now, when else? This is just one stage in a child's lifespan. That job would always be there for you if it is destined for you or you would find something better. Take one day at a time, nourish, nurture your child.
On the other hand, some babies have problem swallowing, call for medical attention. Try to give pure water to clear her throat for any dislodgment. If is a big child, breast milk will not fill her up so fast, do both bottle and breast-feeding. Some big babies start taking semi-solids as early as six months. It could be the baby is not satisfied with bottle-feeding or do not like the taste.
Also, you might want to change the baby-food. Try a different formula. Your baby might be allergic to ingridients in the current formular. Most babies like similac with iron.If condition still persists, check her for possible sore-throat or tonsillitis with a pediatrics or family physician and treat the cause.
Ask your employer for more maternity leave. He or she would understand. We are all humans.
Goodluck,
J. I.( a mother of three grown children).