I need help with my weight!!!!?

I am now 24 weeks and 6 days pregnant. Before I got pregnant I was under weight. I am 5'3 and I was 108 pounds. I am usually 125-130 but due to stress I lost weight. I am now 122 pounds. I always hear from my mom that im too small for someone as far as I am. Most people didn't even know i was pregnant til maybe 2 weeks ago. I have gotten bigger and my belly shows now but im am afraid that I am hurting the baby because i haven't gained alot of weight. I had lots of morning sickness in the beginning of my pregnancy lost 2 pounds but got them back. Im not a big eater. I take prenatal vitamins but I am wondering what else I can do? Maybe there are drinks out there that can help since i don't eat a big meal. i do drink ensure once a day. I am not aloud to walk due to the baby begin so low they tell me to elevate my feet. So exercises are out of the question. Someone please any suggestions will be great. I am afraid the baby or I wont gain the proper weight.