yh thats pretty normal, but a little slower than average. looking at your comic, the premise is cool and the art is definitely passable - hows your promotion? people cant subscribe if they dont see your comic. you should get some promotion on twitter and tumblr down - 1980s werewolf stuff is a very tumblr-appealing thing, and twitter has lots of opportunities to plug webcomics
that said, i gained subscribers blimmin slow. i have 300 subs now and ive been posting just under 2 years - my first few chapters were pretty hard to read, which holds me back. other people i know got that many in six months, but were riding on the momentum of a previous series or short and had more experience to begin with.