My doctor says that my egg size is small, which medicine may i use to make it appropriate and for how much time.

Tricky: Although Clomid (clomiphene) is sometimes used for this, there isn't a large body of evidence for many drugs increasing egg size. There is an interesting new procedure, however, called in vitro activation, that you can read about here: http://www.foxnews.com/health/2013/10/01/new-fertility-technique-can-induce-egg-growth-in-infertile-women/. Also lots of water and exercise and a multivitamin help egg health.