Could i take vitamin b complex while taking prenatal multi + dha, d3 1000iu, and evening primrose oil 500 mg and breastfeeding? or is that dangerous?

Why: You can take these medication while breast feeding, but as i'm sure you've read, it's so much better to try to get your nutrients from real food, fruits, vegetables, etc., than from supplements. Your body absorbs better and you're not exposed to possible additive ingredients. See if you can make changes to diet before spending money on supplements.

Not dangerous at all: All of these supplements are perfectly safe to take while breastfeeding. However, as fall approaches (and already at your latitude) it is impossible to get adequate d from the sun and most adults need 5000-8000 iu of vit. D per day to achieve optimal levels.