Please Help!

My 18 year old sister just revealed to me that she is having a pregnancy scare. She told me that she has been having some positive at home pregnancy tests but when she went to the doctor today, they told her she wasn’t pregnant.

I’m terrified that my younger sister is pregnant and I’m so concerned it’s going to stress OUR MOM and our family out beyond measures and in many ways.

What could this mean? Are the at home pregnancy tests wrong or are the doctors wrong?

Any help or advice on this matter would be greatly appreciated.

Thank you!

Sincerely, a stressed out older sister