Pregnant or naw?

Rebecca • My nick name is Becky. I am 13 years old. I play soccer an take it very seriously. I`m known to be fun and funny. :P :)
Okay, so my friend has not had her period last month and some of this month until I started which was the 10th I believe so that's more than a month, but then, she told me her period stopped 3 days later and was light. Usually, her period comes at the end of the month and is heavy. She told me that she has been throwing up and her head spinning. I asked my mom(she is an RN) and she said for her to get a first response test just in case she was pregnant. She doesn't want to ask her family to take her so me and her are going to save up money this week and put it together, o to our other friend's house and see if we can purchase one while we are there. My question and need for advice: do you think she could be pregnant? She has said she hasn't has sex. Will we be wasting time/money? Or should we wait? Or what else? We need help! This is all I have left to find help from. We are only 13 almost 14 years old!!