Are you naming her after someone?
I think Jamie is a pretty name, I just think Jameson might confuse teachers (and such) as she grows up since it is typically a boys name.
Jameson origin being "son of James"
I think it's a beautiful name. My niece is named James and it suits her perfectly. If you go on the Baby name wizard website you can see that at the beginning of the 20th century James was also used as a girls name. And of course there is the female model, James King.
As for Jenna Jamison, I can't help you there. I can only say that I've never heard that name before.
Good luck and congratulations!