It's quite possible you're at that slow-down point...yes, all ready.
It took me by great surprise that it happened when I still had so much to go! Right around 200 pounds my losses slowed to about 4 pounds a month on average.
You have to muster through. Four pounds in a month is that recommended 1-2 pounds per week. It's spot on.
I know it's frustrating...I've been there myself for a long time now.
As for suggestions? Keep up with whatever exercise you are doing and work on increasing intensity, not necessarily the time. (Quality not quantity). And unfortunately, losing weight really is about the diet. There's no way around it. You can not exercise off bad food choices or even too much of a healthy food. You've got to get that calorie deficit by not eating over budget.