Wasn't really planning on cosplaying her because of her big boobs lol. I just bought the wig for my Lina Inverse cosplay and while browsing my Facebook, I saw some One Piece Cosplay Group (of Grandline Philippines) that needed a Nami and Nico Robin - Time Skip characters. I know I'm the exact opposite of Nami when it comes to appearance like I have small boobs, my height is only 5' and so on. The only thing that we both matched are being skinny >.< Even though I'm the opposite of Nami, I volunteered to join their group, but of course I won't be wearing a bra only unless that I'll wore a body stocking in it (and right now, I don't have any funds to buy/make a body stocking. Aside from that, I noticed that I would just look like a hanger wearing a bra >.< so I'll resort in wearing a sando with green stripes LOL).Here's a little info about Nami for those who don't know her and for those who aren't familiar with One Piece xD
Nami is a pirate and the navigator of the Straw Hat Pirates. She is officially the third member of the crew after Arlong's defeat, and the second to join. She briefly betrays the crew during the Baratie Arc and rejoins at the end of the Arlong Arc after her past and true intentions are revealed. She has a bounty of

Nami is a young, normal-sized and skinny girl with orange hair and light brown eyes. Many people consider her to be very attractive or even beautiful. She has a blue tattoo (black in the manga) on her left shoulder which represents mikan and pinwheels (an homage to both Bell-mère, Nojiko, and Genzo, respectively), where she used to have a tattoo for being a member of Arlong's crew.
- Her height is 169 cm (5'6).
- Her three measurements are (according to Sanji and series creator Oda in supplemental material) B95-W55-H85 (37"-21"-33"), making her breasts an I-cup in Japan. However, her breasts seem to grow into and then "reset" throughout the arcs (this is much more obvious in the manga and in Movie 7).
Source: One Piece Wiki