Hi I am 24 years old and I have 36dd breast.. I am 157cm in height and weigh 132lbs.. how do I make them smaller as I am very conscious of them

Surgery is about the only real option. Exercise could perhaps firm them up somewhat if there is an issue there.
But to be honest, they don't sound that overly large.

Thanks chuck was thinking I would get the surgery reply... well I have recently started exercising and hoping it will be all right... will keep this page updated if it helps

Well they are already grown so you can have surgery done. If you were still 17, that would lead to abnormally shaped areas.