Creams or massages will not help much for firmness of your breasts.
Go for finding the reasons for loosing your weight like any chronic illness etc.
Take high protein diet like milk, cereals, pulses, puddings, cheese, panier, butter, ghee etc.
Take some protein powder.
This will help to built your breast mass giving you firmness and well shaped breasts.
Rule out thyroid
Ok and take care.