Ugh...weight gain

Anyone have any advice for slowing down weight gain?  I have managed to gain 32 pounds and I am only 25 weeks and 5 days.  I am not over eating and hardly eating any sweets or junk.  True story.  I do not want to go on a diet, because my doc advised me not too.  She doesn't seem to worried about the weight gain, but i am horrified.  I feel so big and I am only 5'2....I am really starting to feel it. At this rate I will have gained 50 lbs when I deliver.  That is very unhealthy and I am a healthy person.  I was working out, but I stopped because it was becoming too difficult.... I couldn't get through the workouts... I couldn't breath and they were too hard even though they really weren't and were prenatal workouts.  Nonetheless, I don't know what to do and I feel very uncomfortable and overweight.  I mean a belly is one thing, but my thighs, butt, and back have so much more fat!😳I usually weigh  a fit 120!