The United States Breastfeeding Committee (USBC) has a Breastfeeding Advocacy HQ page on their website. It includes:
Current federal legislation – House and Senate bills – that affect breastfeeding.
Partner Materials about the federal legislation – action alerts, toolkits, fact sheets, …
USBC General Action Alerts
Partner General Resources
Toolbox for Breastfeeding Advocates – Resources, Lobbying Rules, and General Handouts for Legislator Visits
Signing up to receive USBC Action Alerts is a good way to stay on top of breastfeeding legislation.