My DD is 18 weeks old and, until now, has been exclusively breastfed. However, I'm trying to finish my PhD so my mum has offered to take her out a couple of times a week to give me time to get on with my work. I find expressing quite tricky and find that on days when I express, there seems to be less milk for DD, which is far from ideal. I'm thinking of sending her off with mum with a bottle of expressed milk and a bottle of formula, for back-up. I will then express to relieve engorgement if necessary. Has anyone had any success using formula just a couple of times a week? Many thanks