7 months pregnant and losing weight?

I found out I was pregnant 2 months into it and hadn't gained but 2 lbs, than the next three months I gained 50 lbs. The sixth month I leveled off and maintained my weight.. And this seventh month I dropped between 7-10 lbs and its really only been a couple weeks into the 7th month, my weight fluctuates a lot but is steadily dropping. I eat when Im hungry, most of the time.. But I have been extremely stressed and emotionally tried in this last few weeks by things I cant control and havent had much of an appetite. I gained too much at first, is it really that bad to be losing weight during my last months when I will be overall at a healthier weight? I make sure to eat lots of protein and veggies and take a prenatal vitamin daily. I also work over 40 hours a week on my feet and running hospital halls, this started just the last two weeks also due to financial hardship I had to increase my work hours from very little to overtime and therefore increased my exercise. Interested to know what people out there think after weighing all the data. I am 5' 7" and now weigh 180 lbs. maximum weight ever, 191 lbs. Starting weight before pregnancy 140 lbs.