Sue, breastfeeding works on supply and demand, so the very best way to increase supply is to feed more often. If you can, try to start most of the feeds on that side, and you might even like to try offering that side between feeds for a couple of days. It could take a week or more to build back up but your DD will get enough milk in the meantime as the other side will be producing more to make up for it.

This is pretty common hun, and you are doing a fantastic job