Breastfeeding boobies

I have a naturally large chest and plan to breastfeed. Nothing will change my mind about breastfeeding but I've had some people comment when I mention it telling me that after I'm done breastfeeding my breasts will look nasty saggy and deflated. Is this true? Prefer naturally larger chested women (D and up) that have previously breastfed to answer but any momma that had breastfeds input is welcome.