breastfeeding Advice😩

So I've been breastfeeding my daughter for about 5 weeks..now around the ending of the 3rd week I saw I wasn't producing much milk out of the left breast so I strictly on nursed her on my right breast Only.But now my left breast is extremely small like there's absolutely nothing in there while my right breast looks larger than life.I want to be able to nurse off both breast but I feel since I stopped nursing her on the limp breast there's no way I can build my milk supply back in that one.What can I do???????