keep on and never give up, if you feed them more formula milk, you will produce less milk, I have the similar experience, I feed my bb much formula milk in her first few mths, turn out she gets much fatter and I produce less milk, I feed her all my milk after she intakes solid food around 6 - 7mth old, I stop feed her formula milk till now, she is nearly 21-mth old la and she still drinks my milk, so my experience tells me, don't think too much but just go ahead to feed her your milk directly, you can produce enough of what they need, after they can eat congee/rice later on, you will easier and comfortable