When they grow during puberty or by gaining weight and hope the fat goes to the bust or by getting pregnant (but then it's temporarily). There are no cremes or massage etc, those are all myths.
No.
by having sex
Your bust size can increase with exercise, gaining weight and protein supplements. You want to be careful not to gain weight in the wrong places.
Play with them.
Birth control
No it wont increase her bust size. Maybe she just doesn't want you to?
I have read once and heard it on tv that eating papaya (Carica papaya) can greatly increase bust size and studies have shown this to be true.
size 12
By getting pregnant.
Get pregnant. Then your breasts will increase.
No. There is no medicinal way to increase or decrease the size of your bust.
There is no specific bust size for a size 18 woman. The average bust size for a size 18 woman is 109 cm/43 in.