Well done for you weight loss so far! I am also obese and have ~80-90lbs still to lose.
Remember that all the diets you might have tried before are different and perhaps they didn't work before because they are not sustainable, not that it was your fault. I find Primal eating is sustainable as a permanent way of eating because I enjoy the foods and don't crave junk food as much as before. It's a lot easier to find the willpower to keep going or to come back from the occasional slip-up, when you have an enjoyable healthy diet to go back to, not some painful fad diet!
There is a 'Significant Weight Loss' group you can join here: http://www.marksdailyapple.com/forum/group11.html