What Is The Normal Size Of Penis?

hello doctor, i am indian and i am 18. my penis seize when its erect is 5.5 inch. and when my penis is normal, the forskin can be unwraped easily, but when my penis is erect the forskin does not unwrap completly.... sir my questions are:

1. is my penis size ok when it is erect?

2. how to unwrap my forskin completly when my penis is erect?

Thank you.