I am 20 years old .i have a gf many times we are physically attached. But my tell me she doesn't satisfied with my size because she not feel pain pand pleasure .means my pennies just go and come so she tell me improve the size and stamina sperm come out in less than 5 minutes so I am very worried .my size is 5 inch please help me how can increase size and stamina. She satisfied with 7.5 inch size please help me.