Also I've heard it's better to breastfeed and smoke than formula feed and smoke so that kind of puts me at ease if/when I do

Kellymom says if you smoke immediately after a feed then wait at least 30 minutes, you will be okay to feed again. And of course changing your shirt, washing your hands, brushing your teeth would help reduce smoke getting on your baby. As far as smoking cannabis I've heard it's generally safe all around, although I usually wait a minute just in case.