Don't get me wrong, I was absolutely bloody minded that I was going bf DD, and I did. Bloody mindedness is a great approach if you really want to bf but there are some circumstances where a baby's health may be compromised if you absolutely refuse outright to give any ff. I'm not talking about the first few days, you might be persevering through those first few days and understand that babies come with a fat store which means they don't instantly need milk. However, it might be 3 or 5 weeks in and despite feeding around the clock your baby is not producing wet nappies, their eyes and soft head patches are a bit sunken and their skin isn't as elastic as it should. You don't have access to donated milk what would you do?
ETA: You're also taking anything and everything you can to increase supply. The only reason you don't express is because you have a baby permanently attached to your boobs.