29 almost 30 weeks and not gaining weight

So I went to the Dr the other day and I've only gained 3lbs. The Dr wasn't worried at my 24week appointment when I had only gained 1lb but now that in 4 weeks I've only gained 2more lbs he is starting to worry. I'm still getting sick about once a day so he put me on Zofran again and something else. He said everything is measuring where it needs to be. He measured my belly and it was 28cm and my baby girls heart beat was in the 130-140 range. My glucose test was 106, he said they worry when it's 140. I got sick that morning after I ate so I ended up doing the test on a empty stomach. Okay sorry for rambling but do any of you have ideas or things I can eat or do to help me gain some weight? I try to eat but I get so full after only eating a little and if I try to continue I feel sick! I try to eat small meals every 2-3 hours. So I'm not really sure what else to do. I also get full after only a few bites of food and will fell/get sick if I keep eating. TIA!!