Losing weight in 2nd trimester?

14 + 3 with my second baby. I haven't gained any weight since my last prenatal visit (4 weeks ago) but have lost weight. I had lost about 5 pounds due to mornin sickness in the beginning of my pregnancy. Although I'm not sick anymore I'm STILL dropping weight. As of yesterday's prenatal visit I was down another 2 pounds.  I eat several small meals during the day and drink tons of water. I also indulge in junk food 😩 
My doctor has put me on an eating schedule, but it's really not different that what I've been doing. She doesn't seem extremely concerned right now, but says it's important I'm gaining enough?
Anyone else going through this? How did you get through it?