Question about low milk supply-do small nipples&breasts affect supply? Shall i nvr sleep & nurse baby frqntly ?

No you aren't doing it right. Your breasts are never empty, and as long as you are nursing you will produce milk. What makes you think you have "low supply"? When you "top her up with formula" what you are telling your body is it doesn't need to make milk. If you stop all formula and just put baby to breast when she is fussy your production will increase. At 4 weeks she is at growth spurt age also, which is a time when they want to nurse frequently. They tend to do what is called "cluster feeding", and at those times they can want to nurse several times an hour. This is normal and what baby is supposed to do. As long as baby is making wet diapers and gaining weight your production is just fine. One warning, don't fall for the pediatricians "booby trap" that they may tell you baby isn't gaining "enough" weight. Most pediatricians only use the standard charts for formula fed babies, and have no clue how a breast fed baby is supposed to progress. If you want to form a fully breast feeding relationship stop all bottles and formula and just put baby to breast on demand.