Too much weight gain


I'm 17 weeks and I've gained 10 pounds already. I walk a lot more now and go into the pool for a little a couple times a week. Will more exercise help me lose some of the extra weight or does it slow down the weight gain? I started at 135 and some days I'm up to 145-150. I only drink water and eat fruit and mostly healthy with 1-2 cheat days a week. The doctor said I should only gain 25 pounds total!