is it breastmilk bottles? she does not have to work as hard to get milk from a bottle so maybe that is why she is taking a preferance to the bottle or maybe it was just a off day my daughter was exclusively breastfed and refused a bottle all together but she always prefered the left breast over the right which is very common babies prefer one side
If she's getting bottles all day, and only nursing once, I think she's developed a preference for the bottle. Like Samantha said, the bottle is a lot easier, and a lot more comes out at once. And yes, they also usually have a favorite side. When I offer my daughter my right side she frequently says, "un unh, boobie" while she's pointing to my left side.
My son started doing this in the middle of a transition. He was moving himself from eating 20 min each side every two hours to 10-15 each side every 2-3 hours. As they get older their sucking reflex is stronger and they can eat more efficiently and don't need to stay on as long or as much. She is probably just getting more faster so not needing the same schedule. Unless she stops eating I don't think you have anything to worry about :)
pump more your supply will come back i quit breastfeeding for 2-3 weeks my child was much much older than yours... 23 months but istarted to breastfeed her at night sometimes again it hard to get your milk to just dry up pump more and you will make more good luck