Weight frustration rant

I don't understand why I keep gaining so much weight! I mean obviously I am pregnant but I am 25 weeks and just found out I've gained 20 pounds already! I eat healthy and walk every day for 2-3 miles. Everyone keeps telling me that I look great and that the only weight I've gained is in my stomach where it should be so why does the scale keep going up!! I have a friend who is also pregnant and has gained a lot of weight in her legs arms and face but has only actually gone up 15 pounds on the scale and she is 30 weeks :( I was a college swimmer and a Triathlete before getting pregnant and have always been very good at regulating my weight... I hate feeling this big!!!!! 😡