Will supplementing decrease overall supply?

kelleynb28

I was just about to start weaning my 4.5 month old (due to weight gain issues), and have come to an abrupt halt. I have always given him a formula bottle at night before bed and have switched one feeding around noon for a formula bottle. So my schedule looks like this:

6:00am - Wake up and breastfeed

8:30 am - Breastfeed

9:00 am - Nap 

11:00 am - Breastfeed

1:00 pm - 7 oz of formula

3:30 pm - Breastfeed

5:00 pm - Breastfeed

6:30 pm - Breastfeed

7:15 pm - 7 oz of formula

7:30 pm - Bed for the night until 6:00 am (I do not pump anything during this time) 

This schedule seems to work well for us and because he has recently gained 10 oz in 2 weeks, I planned on sticking to it. However, my lactation consultant tells me that if I was to continue to breast feed AT ALL that I am going to have to wake at least 2 times during the night to pump and will have to pump at noon for the bottle I am giving or my entire supply will eventually diminish. 

I thought that your body will regulate itself to only supply milk during the times that your baby needs it? I know there are people out there that only nurse once or twice a day! Any thoughts?