Breast milk to formula

Victoria

I am a 20 yr old first time mom with a 5 week old. My milk supply has reduced so much. I’m only able to pump 2oz. I am so upset. How do I switch from breast milk to formula? Any tips? She’s also having a hard time pooping she’s only pooping 1-3 times a day so I’m also scared to do the switch but I have to due to my low supply :/ im going to get her started on the yellow enfamil can of formula, is that a good to do the switch with?