Should I worry

I went to the dr for my anatomy scan and they told me that the umbilical chord is off the the side of the placenta. I’m 21 weeks and 5 days and my baby girl weighs 13oz. On top of the umbilical chord position it only has one artery and a vein instead of the normal two arteries. Has anyone else experienced this? What was your outcome? I’ve been doing some research but it makes me worry. The dr told me not to worry until complications arise but that just makes me worry that there will be complications. I had complications with my first and I don’t want anything to happen with this one.

UPDATE:

I went to see the high risk dr on Wednesday and my sweet girl is a little over 4lbs and growing great. Her abdomen is only 8th percentile and they said they don’t like it to be below the 10th but she is 18th percentile for overall growth so they aren’t too concerned right now just closely monitoring her growth. I am having a hard time trying to comprehend that my baby could be here in just three short weeks if her growth decreases. I have started having Braxton Hicks contractions that make me ache so bad it’s hard to move but at the same time I can’t be still for the restless leg. 6 weeks would be ideal because I will be at 40 weeks but because of her size I am willing to let them take her a little early. I am hopeful that she will be at least 6 pounds where my first was only 5.5. As long as she is healthy I am happy.