How to prevent milk drying up?

With my first baby she never nursed well (she had colic) so my milk started to dry up around 8 weeks and was completely gone by 12 weeks. With my second we have had an easier time, I've been able to nurse and pump more than enough. But in the last week my milk seems dry around 9pm and I have to give her the milk I pumped during the day. It only happens at night, but I'm worried about drying up, she's only 10 weeks old. Any help or advice? we only have one car so it's hard for me to get in to see my lactation consultant.