Re: Relactation after 4 months
This link has a lot of useful techniques for getting a previously weaned baby back to the breast: http://kellymom.com/bf/concerns/child/back-to-breast/.
I just want to encourage you and to say that what you want is possible! You still have milk, and that's a huge head start in the relactation game. But even if you were completely dry, relactation is possible. My mom managed to relactate after 3 months of not nursing and not pumping. She just started putting my little sister to the breast, and within a few months she was able to completely drop the formula, and went on to nurse my sister until 18 months.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"