My sagggg :/ how can i make them not !!?

okay so im 17 & i used to have pretty big s & for the most part perky but then i lost a TON of weight and they started saagging i regained some weight but they still sag & they arent in the front they like departe & go to the side so its really embaressing to ware bathing suits so what can i do that doesnt cost money that will make them be more perky & to be in the front & not go to the sides.