Weight loss in third trimester...

So through out this whole pregnancy my weight has dropped and dropped and dropped. Starting at 215 then 200 then 189. Finally in the last 8 weeks I have put on 8 lbs. Well in the last week my iron supplements had to be doubled, which I thought would constipate me, but somehow has the opposite effect. I have been going to the bathroom allot, everytime I eat basically. I have lost 3lbs this week.

I wad going to speak to my Dr, but I had to move my appointment to the 22nd instead of the 16th. (My boss said her meeting was more important.) Anyway, I just want to do what's best for my son and I know that losing weight can't be. I don't want anymore complications, because the first trimester and half of the second were terrifying. I just want a smooth pregnancy from now until he is here.