Breastfeeding, help!!!

J
Since I've been home with my Daughter for the first two months of her life we've been primarily feeding from the breast. I love the quality time and let's face it it's much easier than waiting while the milk warms in a bottle. When going to the doctors and to family gathering we have used a bottle of breast milk though. I feel like now that she's a bit older she is more reluctant to taking a bottle and prefers to be on me. Which isn't a problem until now.  I start back to school on Monday with my mother watching her during the week. I'll only be gone two to three hours each day, but want to know advice for getting her to take a bottle of pumped milk. We use the Kiinde system that worked wonders in the beginning. Sometimes though she is just not having it with a bottle. It's my biggest fear, being in class and she's crying wanting the breast and is hungry. Please any tips for successfully switching to bottles. She takes them sometimes.. But not always.