Is it healthy to take enhancement pills?

I'm 18 and have a very low self-esteem because my chest is barely and A cup. I think I'm pretty much done growing. Is it okay if I take enhancement pills. Like what are the later or side effects of taking these pill ?Can it become addictive? Will my shrink once I stop or is it permanent? Is it okay for nursing later on? And lastly if taking it is okay which product do you recommend?