Worried and confused

I was in the hospital all night last night because I was feeling pain in my anus. They did alot of test on me and everyghing is okay. They did an ultra sound on me and said the baby is okay and in the right position. However they are saying the baby is small so maybe I am not 7 weeks but maybe 5/6 weeks. They had to increase the image to see the baby. Tell me what you guys think.