20 weeks weight gain obese.

So I’m not sure if it is water weight fluctuations or what. I have been okay at keeping my food intake at a normal rate not taking in extra calorie snacks, late night snacks, excessive portions. However I have gained 10 pounds already somehow. I have recently gained about 5 and I have grown quite a bit needing maternity clothes. This is my third kid. I started pregnancy around 208/210. As of this morning I am 218 and it made me cry I have been so good. I don’t understand. I swear the other day I was 213. I was 242 at the very end of my last pregnancy. I dont want to get there but I am on the road there. It seems my body just gains weight and I can’t help it. Anyone else experiencing this? Or anyone have advice? Anyone have success stories of losing weight after baby. This is my 3rd and my last two are only going to be 18 months apart almost to the day.