I will add - we used Save our Sleep when DS was switched to formula. I don't know about the effects on breast feeding.
My son learned to self settle at a young age as I said. He is now 3 and a happy healthy boy who has no issues with sleep and can be asleep within 5 minutes of his head hitting the pillow. He also still sleeps 2 hours during the day. I just wanted to give you a different option and perspective.