AOA Dr. Sb

I would like to get some information regarding penis size, whats the normal size? 

is tehre any medicice or exercise to increase penis size and also thickness? 

second problem is that erection from last some months i feel that my penis is not ericted properly and if it erected but time duration is lettle.

please advise me what can I do? would i take some medice or need some exercise

trhnKS 

Regards