Breastfeeding mamas, supply and weaning

Hello. My little one is 9 months about to be 10 months. He lately won’t nurse or does for very short period of time, this causes me to pump and feed him. I feel like I’m either not producing enough for him or he’s just over the boob ( which with my first never happened) I’d like to make it to a year especially with COVID but I’m worried I can’t keep up because I’m one pump I’m getting only 5oz.... if I’m lucky. He usually drinks 5 oz every 3-4 hours if he doesn’t nurse. Should I slowly transition into formula to supplement . He’s eating solids 3 x a day as well. Thanks!