Babies head circumference small?

S 👩🏼

I am 23 weeks pregnant and have had my 20 week scan and another growth scan, both times my baby girls head was measuring small the last scan she was on the 1.5 centile which is tiny and her femur length is 3.8 centile. I am going back on Monday for a more detailed scan and to check my placenta. Also waiting for some blood results to come back to check for any infections. They said they will discuss doing an amniocentesis test on Monday but me and my partner aren’t keen on that. Just wondered if anyone else had similar stories or advice!?