What the hell with weight loss ..

So im 36 weeks pregnant... Since 5/21, I went from 186 down to 174 as of today... I'm so confused. Note, I have been diagnosed with preeclampsia, and am being induced next week as long as all my labs come back looking good. .. or at least little to no dropping. Also, over the last 3 days I've been dealing with my blood pressure dropping (obviously not low enough for me to go to the hospital about it, but lower than my norm) dizziness, being lightheaded, nauseous more than normal... And really bad headaches along with seeing spots in my vision occasionally. My doctor said that could be from being dehydrated (but I've been drinking quite a bit of water lately...) my body is so out of whack right now, idk what to do. I haven't changed my eating habits. Like, I HAVE to eat. Literally. Of course, I'm not gonna eat more than I can handle in one sitting. I haven't really had a LOT of swelling. (Literally, just enough to say I was a bit swollen .. haven't been swollen in 2 weeks thanks to the blood pressure meds) I have been peeing a lot, especially at night. Like... What can cause me to lose so much weight so fast?! I'm at a loss. Because I know I didn't have THAT much fluid on me. At least I don't think I did...