I Am 36 Yrs Old Having 3.5" Erecting Penis. Tip

I am 36 yrs old having 3.5" erecting penis. Tip of my penis is very sensitive at intercourse and ejaculate after some time. So I use manforce 50mg / vigora 50 tab for long time. Is it problem for future. I have used since 6 months. Any other options pls tell me. My weight is 75kg and 5'3" height. Again tell me how can I enlarge penis size both length & width.