Hi there! Thanks for your questions, here’s some bacon to enjoy while I answer. 
The Bloodfang Pack 
Yes, you can indeed roleplay as a worgen that is currently or formerly part of the Bloodfang Pack. The Bloodfang Pack began when Archmage Arugal summoned Alpha Prime and other Kaldorei-worgen into Silverpine forest. It grew in number in the shadows of Gilneas by initiating willing Gilneans, many of them criminals and former Northgate Rebels. The Bloodfang Pack now consists of both human-worgen and kaldorei-worgen, and while they were responsible for orchestrating the worgen attack on Gilneas, they have worked with the Alliance both in the Silverpine Forest questline and in recent days in Darkshore and Silverpine.
You could roleplay a Bloodfang Worgen in several different ways. You could play a Bloodfang Berserker type character, a primal fighter and powerful force against the Forsaken that has taken part in the conflict in Darkshore. Second, you could play the stealthier type Bloodfang, the likes of which used human form in Gilneas (see Curse of the Worgen issue 1) to sneak about the city unseen. In either cases, if you’re serious about the character and want to learn more, you can read Curse of the Worgen, do the horde Silverpine Forest questline, and examine the Shadowfang Keep dungeon.
https://wow.gamepedia.com/Bloodfang_pack
https://wow.gamepedia.com/Silverpine_Forest_storyline
https://wow.gamepedia.com/Shadowfang_Keep
https://wow.gamepedia.com/Curse_of_the_Worgen_(comic)
The Moonrage Pack 
In addition to the modern Bloodfang Pack, you could indeed roleplay as a former member of the Moonrage Pack you find in Pyrewood Village. They have been exterminated by the Forsaken, but even in exterminations there are some surviving stragglers (see Apothecary Berard / Berard the Moon-Crazed, and Lost Son of Arugal). However, a Moonrage Worgen would be played differently than a normal worgen, since they get their curse from the cursed “Pyrewood Shackles” they wear in their servitude to Archmage Arugal, which cause them to all become worgen at night, and human by day.
https://wow.gamepedia.com/Moonrage_pack
https://wow.gamepedia.com/Arugal%27s_Folly
https://wow.gamepedia.com/Lost_Son_of_Arugal
https://wow.gamepedia.com/Apothecary_Berard
https://wow.gamepedia.com/Berard_the_Moon-Crazed
Thanks for your question, here’s more bacon 
Please so come back to me and ask if this raises more questions.