Are u talking about Plan B, or regular birth control pills that u take daily? If ur talking about regular pills, u can take progestin only birth control pills, aka mini pills. As progestin only methods typically don’t mess with ur milk supply. As far as Plan B goes, that pill is progestin only as well, so it’s fine to take while breastfeeding if u truly need to take it.

The mini pill and iuds are safe for breastfeeding

To be safe, I’d ask my doctor.