Yea, considering the next highest Leapord skin cat (yellow, not blue) is lvl 44 minimum.... it makes me wonder why i dont see a lot of that beauty running around, i myself couldnt click... perhaps others couldnt click or wanted the loots more.. -shrug- for a worgen though... if you want to stay within a matching color palette, and if you plan to BG a lot...

lvl 23-24 in Duskwood

lvl 18-19, found inside Wailing Caverns, unless you find a group whose willing to let you tame, having a friend run you through will work

lvl 10 in Teldrassil, lvl 18 rarespawn in Loch Modan, lvl 19-20 in Ashenvale (theres more that would work too but im freaked out by the models so you'll have to go through em yourself hehe)

or

or

Red one: lvl 8-9 Tirisfal Glades, Tan: lvl 26 inside Razorfen Kraul, need either a friendly PuG or a friend to get you through, White: Ressan the Needler lvl 9 rarespawn Tirisfal Glades

lvl 9 in Durotar, lvl 15-17 in the cave leading up to Wailing Caverns (not the dungeon itself), lvl 18 in Barrens (around Humar the Pridelords spawn area, his name is King Reaperclaw, he has 2 raptors following close to him), Takk the Leaper lvl 14 rarespawn in the Barrens (originally was 19 elite but not now), WoWhead can give you a picture location, also dont forget to circle around all trees right up till you end up at the nasty venter co. base with that oozing lake for a chance at the nest, it has a minipet you can learn or sell
Vanilla Crocks:

or

Grey: lvl 10 Durotar, lvl 25-26 and lvl 26-27 Northern Stranglethorn Vale, White: Deviate Crocolisk lvl 18-19 inside Wailing Caverns (need a nice party who will let you tame or have a friend help you), lvl 22 Wetlands (i think its a quest target... its named Horrorjaw)
Or...
Cata Crocks:

or

Green: Gosh-Haldir lvl 15 rarespawn Loch Modan, Blue: Mahamba lvl 28 rarespawn Northern Stranglethorn Vale

Tsul'Kalu lvl 28 rarespawn Northern Stranglethorn Vale

lvl 10 Spawned Azuremyst Isle. Need to kill the nearby ravagers until the key to its cage drops. The key doesnt break after use so you can store it away in your bank if you want to hold onto it or destroy it. You can always farm a new key from the ravagers.
If you are Beast Mastery the Dog family isnt really a good idea because it restricts the use of Kill Command when they are channeling their Lock Jaw ability (that is, if you even use the Kill Command! I dont and i know i should >_>;;;;;;)
These pets are all under lvl 30 since you are still starting out, and they're all families i myself would pick for PvP, but dont let it restrict you from choosing a pet, if you want to use a cat, use a cat! or a wolf or a tallstrider or a bear, its all up to you, just as the color scheme you want is yours to choose :3