On diet while pregnant?

Hi ladies! I have a problem. Since my last child(April 2015) I have not lost any weight , and I'm still overweight not too much but I really hate how I look and no confidence at all. Right now I am 88kg and I am afraid that I will go more than 100kg at the end. I have never been so heavy in my life. Is there some kind of diet I can use now or exercise (I haven't done anything since November)? To be honest I really can't wait when the morning sickness will start at least then I will lose at least 2kg. I'm so depressed right now.

Thank you for reading! Have a nice day.:)