Since you're starting out, and based on your weight/height, I'd say you should look in the range of 141-146. Shorter will be easier to maneuver and initiate turns. My girl is just an inch taller than you and similar weight, and I put her on a 145.
I'd suggest looking into Gnu, Roxy, Never Summer, Arbor, and Bataleon. They all have some great women's specific boards with cool graphics too.
18 Snoplanks Asym Fish . 18 Arbor Terrapin . 17 NS Maverix . 17 NS Twenty Five . 16 NS Swift - 14 TJ Brand Retro Fish
18 Rome Katana . 17 Burton Malavita Wing . 16 Burton Genesis X
16 Flow Talon