看语法有错没?

语法有错，改为This is my first time speaking English with an important person who may decide my future direction.
这样说可以，没啥不礼貌的。

语法上有一点点问题。我帮你修改下

It's the first time for me to speak English with a very important person who may affect my future and my life.
It's my honor and also it makes very nervous ane excited.

我帮你加了句，这是我的荣幸，也让十分紧张和兴奋。

This is my first time with my honor (to) speak english with a(an) important person who may decide(d) my future road direction.
这样比较好些吧。