either you are lying and / or aren't exploring advertising solutions aside from AdSense. my forum gets around 5000 UVs in a very crowed niche and I make $800 a month. CPM all the way for forums.
I own a forum that gets just 350 UVs/day and 6,000 pageviews/day and make just over $1/day. Hopefully that gives you a more realistic view on what a forum might make, though it depends on the niche and such.
Why are you making so little? I own a forum that receives the same amount of traffic and I'm making over $5/day.
Oh, it's alright. I thought your writers forum was a lot bigger. So, you'll make at least $10/day from it a few months. Good luck!