Switching between breast and bottle can be very difficult, especially at her age. She is developing what is called nipple confusion. Eating from a bottle is much different than nursing at the breast.
Is she only taking a bottle when you are not there? I would try to make sure this is the case. I would try nursing her right before you have to leave so she might go a bit longer into the time that you are gone.
Another thing you can do is try to feed her before she starts to really fuss that she's hungry. That way, she might not scream as much. It's a combination of her being hungry and not realizing that she is not eating from a bottle and needs to work some and her getting frustrated that is causing all the screaming. Babies won't eat well when they are that frustrated. One way to help her along is to compress your breast with your hand when you are trying to get her to latch on. That will make it a bit easier for her to understand that there is milk there. It will also stimulate her to suck more instead of just expecting the milk to come easily like it does from a bottle.
I hope this helps some. You might also want to consider talking to a La Leche League leader. They can be very helpful in situations like this. Keep up the good work. Breastfeeding can be challenging, but is so rewarding in the end. :)
God bless,
A.