HI! I also got pregnant but about a year after GBS and my daughter was born prematurly at 30 weeks. The Dr also told me she wasn't growing properly they told me she would be born before term. It was my first child after 2 miscarriages and I was very scared. She was born 10 weeks early & her weight was 1lb and 10oz. She was very tiny and not fully developed, but she made it, she was 7 weeks in the hospital and was out before the 40th week and she only weight 4 lbs when I took her home. She is my miracle baby. She is now 2 1/2 years old and is doing well, she is small too compare to other kids her age, her dad & myself are average sizes so I dont worry much.
But Dr's did say she was like 2 weeks behind and she wasnt getting the proper oxygen from the umbilical cord and this is why she had to come out, she also stopped breathing a few times & that really scared all of us. I had no idea I was having contractions until they told me, she was born c-section.
Many people too told me I was having this problems cause of the GBS, but my Dr also said it had nothing to do with it. I was taking my prenatals, my uterus is just not working properly cause I already have a history of 2 miscarriages so you will be fine. Plus now in days the hospitals are loaded with new technology and your baby will be fine.
I just went to the UCSD premature picnic they have every year, it was nice seing all those miracle babies with their love ones, I love this picnics because they are inspiring. That is where my daughter was born the UCSD in Hillcrest, they are the best in San Diego, CA.
Good luck and dont stress or worry, maybe your baby is just small like you said. She doesn't want to be overweight LOL.
