Left breast has dried up

My daughter is 4 months. Recently introduced formular. Because she's generally difficult with the bottle and I have to get back to work soon, I give her the bottle from 07am to 6pm. It's just been 2 days and my left boob has dried up, only my left boob produces milk or engorges whilst she's on the bottle. What do I do? Cause I still want to breastfeed her whenever I'm home with her.