Question about losing weight?

Hi, i just given birth to my lovely boy and gain about 15kg from it. i drop about 8kg during the 1st mth and i need to drop more so that i can fit in my clothes. This is the second mth now and i have started to go jogging 5 days a week and hiking 1 day per week for 2 weeks already. I jog for about 30 mins everytime and eats only 2 meals a day. I eat only fish, vege and friuts every meal and also drink hebal slimming tea. But my weight is not dropping. I went on a weighing machine last night and i gain almost 2kg. What is wrong? is it my diet or my workout? Can someone pls advise? Thanks a lot.