Thanks for your question. Testicular size and volume are genetically determined. The things your mother did cannot have any effect although they have caused you to become unnecessarily anxious. If you are concerned please get examined by an andrologist who can determine their normality or otherwise. Testes do not have to be big and hangy to do the job of making good quality sperm. It is more important to exercise, eat nutritious food, avoid tight underpants and jeans and not to use a laptop on your knees. Your doctor can help you with these queries. best wishes