Confused

So my son is over two years old now. When he was born I breastfeed but due to not gaining weight I had to switch to formula. So I stopped breastfeeding altogether, over the two years I have still been lightly producing milk but I could tell there is no nutrients in the milk. But today I noticed that my breastmilk is starting to have nutrients and I'm producing alot more than I have in the two years. Me and my partner are ttc for #2 and I'm just curious if this could be an early sign. My period starts in five days, I want to test now but I know I should wait til the day of my period if it doesn't show.