Exercise helps me personally lose more weight and helps me get in the right place mentally to eat better, but some people find that they don't need to workout at all to lose. Food has a much bigger impact on weight loss than exercise, but studies have show that it is the most important factor in keeping it off.
I think its best to treat the losing phase the same as the maintenance phase (except for number of calories obviously) so that when you get there you will already have your everyday healthy habits set. I have gotten to goal twice before, but failed to maintain because I had a mindset that what I was doing to lose the weight was temporary and took unhealthy, unnecessary, and extreme measures to get there. Now I am not doing anything to lose that I don't want or can't keep up forever.
Another thing to keep in mind is that for many people the last few pounds come off VERY SLOWLY! Therefore, I don't really think your weight loss has stalled at all. Your body wants to keep those last few pounds for survival and will fight to hold onto them. This is the point where patience and persistence are your biggest allies.
I also don't think you are exercising too much. I work out for an average of two hours a day because I think working out is fun and it makes me feel good. I also do fun stuff like hiking, kayaking, hula hooping, and weight lifting. My only concern is many you aren't eating enough calories to be working out as much as you are. I know it might sound counterintuitive, but sometimes upping calories a little really makes the weight come off faster, especially when combined with exercise.
Sometimes when I need a calorie reality check a daily calorie requirement calculator
is a really helpful tool.