Breastfeeding while pregnant! Help

My baby just turned 4 months old a few days ago and I just found out I am pregnant again. Oops. I went back to work when he was 14 weeks old (currently 18 weeks). A week after I went back to work we all got Covid. Then just yesterday I found out that I was pregnant. I breast feed when I’m home and pump at work but I have noticed a significant decrease in my supply this month. At first I thought it was Covid, then I’ve heard supply decreases if you get pregnant while BF. I so badly want to continue BF for at least a year if not two to both of my babies. Has anyone experienced this? What did you do to help? I usually have oversupply so this is new to me. 🙁