Stubbornness runs in the family–baby has to have it his way

My little one has been almost exclusively breastfed since birth other than a few bottles of formula in the nursery when I was too sore to pick him up and feed him. Since I’m a working mom (or will be when the school year starts back up again) I’d love to continue to let him have breastmilk for as long as possible. However, I’ve tried on many occasions to get him to take it from a bottle. He hates it with a passion. I’ve tried numerous different types of bottles with numerous different types of nipples. When I went to a wedding for like 6 hours, I had to leave him bottles with my mother. She couldn’t get him to eat from a bottle so she had to squeeze the milk from the nipple to his mouth. Now, I know most caregivers are not going to want to do that, nor should they have to. I’m just worried about my little one getting enough to eat on those days I’ll be gone.