Concerned about pregnancy weight...

Amanda • Love being a boy mom, now waiting on baby #2 in October! 1 loss '15, 1 🌈👶🏼💙 '16, 👶🏼💙 '17!
At my last appointment my doctor asked me to start gaining more weight, although she said things are just fine and my baby boy is growing. However, now I'm of course stressing a bit about it. I eat a pretty diverse amount of foods, when I'm hungry. I haven't had a decrease in appetite, although I've switched to smaller meals more often because my heartburn is awful. But now I'm actually losing weight and I'm afraid it will be bad for the baby! I was pretty average sized before pregnancy (5'5", about 130 lbs). Now I'd love some suggestions to boost weight gain? Peanut butter is usually suggested but I hate it and protein shakes make me gag. I'm not anemic, I eat a lot of meat and I'm not on iron supplements.