genitals changing before 20 weeks?

Jenny💙 • christian. wife. mom. step-mom. 💙

so i went to the ER last night for back pain... i have a kidney infection but they still have me an ultra sound, im 16 weeks today. the doctor said he saw a scrotum and a penis and showed me them as well. im really happy because i wanted a boy!!! however, my friend has me freaking out!!! she said his junk can be "sucked back in" before 20 weeks and actually be a girl. has anyone heard of this? should i be worried my boy will turn into a girl?? lol