Hi there I understand your concern... You are just 19 as you mentioned... Breast size increase naturally during pregnancy and lactation I would suggest you to waite till that period...The only way to increase breast size is by augmentation with breast implants which are placed behind the breast through an operation. You need to be comfortable with your breast size and whether you want to undergo an operation to insert the implants...for your friend try to bellow advices...she has to consume less calories and spend more...avoid junk foods,carbohydrates like rice etc,avoid oily foods...add proteins and fibre rich foods to your diet with green tea,green leafy vegetables, fruits...do regular exercise at least 2 hours a day...Consult nearest physician for clinical examination they will do the needful.
Increasing breast size is very tough. But still you can have lactogogous foods in your diet like fenugreek, soya beans and soya products, flax seeds, etc. Also do little exercise and massage for your breast area. Massage should be done in inward round movements 300 rounds per minute up to 10 - 15 minutes. Any queries with related to diet and exercise msg me personally. I would try to help you.