Vegetable diet Day 7

This is the last day of the diet. On the seventh day actually we can eat everything what we eat during the first six days: vegetables, as much as we like, 1 cup of plain yogurt, half of pound fruits, 2 slices of whole wheat bread.
This was too much for me. I ate one slice of whole wheat bread for breakfast. I made broccoli-puree for lunch, and I had a cup of yogurt with strawberries for dinner.
I lost seven pounds during the week but that was not the most important. I feel much better. I have more energy, I get up easier in the morning even when I am up until 1 o'clock in the morning and get up twice during the night because my kids need me. And I do a lot more during the day too. My husband asked me one morning: "When do you sleep?" - because I went to bed when he was already sleeping and got up before him and I still was not tired at all.
And this energy give me the strength to do another week. Only this week on the first two days I put some milk in my coffee because the first week I drank it plain black. It was not too good:D Then on Wednesday I started to put some creamer in it too. But I did the whole week the same way like I did the previous one.

And guess what? My friend wants to do one more week. I don't know what to do. Because I really would like to do it. I just don't know if it is healthy to live for three weeks only on vegetables and stuff. And I don't know what I should eat after three weeks of dieting that I don't gain back all the weight I lost. Or what should I start with?
We already did our weekly grocery shopping today and I bought a lot of vegetables again. So I think I am going to stay with the vegetables and I am going to add a little bit of cheese or meat sometimes and we will see.