My daughter is 4 weeks exactly and I've been exclusively breast feeding her but I don't think my milk supply is enough for her, ever time she eats she's hungry again 15-20 minutes later, and she feeds for around 30 minutes. She gets fussy while eating too like she's not getting anything. My question is, do I have to consult with her doctor if I can give her formule or is it just whatever I say is best for her? This probably sounds dumb but I'm a first time mom and want to know others opinions about giving baby formula and still breast feed her as well. Thanks!