Supplementing with formula

You guys I’m feeling like a shitty mom. I’m going to start supplementing here and there. Because I feel like my supply is slipping. I’m going to keep breastfeeding, but I’m going to try and pump in between when I give him a bottle. So that my supply doesn’t fade. And also breastfeed through the night. I feel like this is best so why do I feel like such a failure? He’s only 12 weeks 😭😭😭😭😭