Decrease in breast milk

My baby is 3.5 weeks old. This past week I have noticed a major decline in my milk supply. At first milk supply was no issue at all… I haven’t changed anything so I’m really confused as to what happened. I’m really stressed and worried my baby isn’t getting enough. I started to pump after every feed ( he feeds every 3 hours sometimes 2 hours) I’m doing this to try to increase my supply.. I only started this yesterday and so far no increase. Most pumps I’m getting 1-1.5 ounces in total from both breasts. My last pump tonight I didn’t even cover the bottom of the bottle. I purchased some lactation cookies to try to boost my supply. As well as I syringe baby a little milk through the day because I’m worried he isn’t getting enough ( public health nurse suggested that when he was first born to make sure he was getting enough). Any tips or recommendations are welcome. This is my first baby and I have no idea what happened… i absolutely love breastfeeding and I’d do anything right now … help 😩