Trouble with 'Olivia'

Although we considered a number of names, including some Chinese ones that would 
also work in America, it was very easy for us to name our first girl Olivia when
I was pregnant as both my husband and I liked the name.
 
When Olivia recently complained to me that I couldn’t pronounce her name correctly, 
it hurt me very much.
 
“Mom, you named me Olivia and you can’t even pronounce it right.” she said.
 
Ouch!
 
So with her and Daddy’s help, I realized that when I say her name quickly, I don’t
have any problem but when I say her name slowly, I tend to prolong the “ee” sound.  
I tend to pronounce her name O-lee-vee-a  rather than O-liv-ia. 
     
I practiced to pronounce it correctly and I have to pay special attention in order 
to get it right, but I still revert to the old pronunciation from time to time. 
It is frustrating.
 
What baffles me is that Evan, who about a month ago couldn't even say her full name 
(he'd call her "Via")  can now  pronounce it perfectly just like all other Americans 
apparently. Is it because he was born here and I was not?