Are you counting your calories? Really adding them up? It sounds like you are eating less than 1200 calories based on what you wrote. Shakes have about 200 calories in them. Breakfast and lunch would be 400 calories. Unless your snacks and smaller portioned dinner is 800 calories, you are not eating very much.

I started out the way you are. I enjoyed a shake for breakfast and lean cuisine for lunch and protein bars for snacks. That worked just fine, but eventually I noticed I was sluggish and constipated. Someone suggested it was the shakes doing that to me. From there I started cutting those things out to a more whole foods approach. Since then I have not had those problems.
As to the other question, I gained 100 pounds with marriage and children. LOL! Weight loss is slow for me, but quite manageable! Don't let naysayers like that keep you from getting healthy!