Breastfeeding Advice

So when my milk first came in, my milk supply was crazy. I had a ton of milk and now that my milk has adjusted to my LO's needs, I haven't needed to pump in a little over a month. I pumped the other day and only made a little over an ounce? Any suggestion to when I should pump and how to increase my milk supply? Also, I haven't breast fed from my left boob in weeks. Any suggestions?