Sudden Decrease in Supply

So almost one month pp my period came back. I have had two periods now and each time my milk supply dramatically decreases the day before it shows up but then goes back to normal a day or two after. This week I had another sudden drop expecting my period to start but it didn’t. Has anyone else experienced a random drop in supply that doesn’t have to do with a period? I’m trying to think of any changes I would have made but it seems like I’m doing everything I always do and there’s no period so I’m not really sure what’s going on.