latching problems

Mkay&Billy2011

My baby just turned three months old and lately I have noticed sometimes when I go to feed her I cannot get her to latch on and eat. It's usually when she is already mad and crying because she's hungry but even when I try to give her my breast to feed her, she just screams at my breast and can't calm her down. It's gotten to the point that I just have to give in and give her a bottle. This is only once and a while though, most of the time she has no problem. I know my supply has decreased and that she gets a bottle while I'm at school. I'm just not sure what to do.